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About WorkSafeBC WorkSafeBC (the Workers’ Compensation Board) is an independent provincial statutory agency governed by a Board of Directors. It is funded by insurance premiums paid by registered employers and by investment returns. In administering the Workers Compensation Act, WorkSafeBC remains separate and distinct from government; however, it is accountable to the public through government in its role of protecting and maintaining the overall well-being of the workers’ compensation system.

WorkSafeBC was born out of a compromise between BC’s workers and employers in 1917 where workers gave up the right to sue their employers or fellow workers for injuries on the job in return for a no-fault insurance program fully paid for by employers. WorkSafeBC is committed to a safe and healthy workplace, and to providing return-to-work rehabilitation and legislated compensation benefits to workers injured as a result of their employment.

WorkSafeBC Prevention Information LineThe WorkSafeBC Prevention Information Line can answer your questions about workplace health and safety, worker and employer responsibilities, and reporting a workplace accident or incident. The Prevention Information Line accepts anonymous calls.

Phone 604 276-3100 in the Lower Mainland, or call 1 888 621-7233 (621-SAFE) toll-free in British Columbia.

To report after-hours and weekend accidents and emergencies, call 604 273-7711 in the Lower Mainland, or call 1 866 922-4357 (WCB-HELP) toll-free in British Columbia.

Blasters’Handbook

WorkSafeBC publicationsMany publications are available on the WorkSafeBC web site. The Occupational Health and Safety Regulation and associated policies and guidelines, as well as excerpts and summaries of the Workers Compensation Act, are also available on the web site: WorkSafeBC.com

Some publications are also available for purchase in print:

Phone: 604 232-9704

Toll-free phone: 1 866 319-9704

Fax: 604 232-9703

Toll-free fax: 1 888 232-9714

Online ordering: WorkSafeBC.com and click on Publications; follow the links for ordering

© 2005, 2007 Workers’ Compensation Board of British Columbia. All rights reserved. The Workers’ Compensation Board of B.C. encourages the copying, reproduction, and distribution of this document to promote health and safety in the workplace, provided that the Workers’ Compensation Board of B.C. is acknowledged. However, no part of this publication may be copied, reproduced, or distributed for profit or other commercial enterprise, nor may any part be incorporated into any other publication, without written permission of the Workers’ Compensation Board of B.C.

2007 edition

Library and Archives Canada Cataloguing in Publication DataMain entry under title:[Blaster’s handbook (Richmond, B.C.)]Blaster’s handbook. -- [2005]-

Irregular. ISSN 1715-2135 = Blaster’s handbook

1. Blasting - Safety measures. 2. Explosives - Safety measures. 3. Industrial safety - British Columbia. 3. Industrial hygiene - British Columbia. I. Workers’ Compensation Board of British Columbia.

T55.3.E96W32 363.11’96234527’09711 C2005-960130-2

AcknowledgmentsWorkSafeBC wishes to express appreciation to the following organizations and their representatives, who have generously contributed time and information to this manual.

Natural Resources Canada — Explosives Regulatory DivisionTransport CanadaDyno Nobel CanadaMaple Leaf PowderJerry Silva

Blasters' Handbook- vii -

Contents

Introduction .............................................................................................. 1

Chapter 1: The Theory of Explosives ........................................................ 3Characteristics ......................................................................................................................................3Effects ...................................................................................................................................................4Properties..............................................................................................................................................4General criteria for explosives ..............................................................................................................7

Chapter 2: Classification of Explosives ................................................... 8Black blasting powder ...........................................................................................................................8Dynamites ............................................................................................................................................8Slurry/watergel explosives ....................................................................................................................9Emulsions .............................................................................................................................................9Blasting agents ......................................................................................................................................9

Chapter 3: Initiating Devices and Accessories .......................................11Initiating devices ................................................................................................................................ 11Safety fuse assembly .......................................................................................................................... 11Shocktube assembly ........................................................................................................................... 12Standard electric detonator ................................................................................................................ 12Initiating accessories .......................................................................................................................... 12Detonating cords ................................................................................................................................ 13Boosters and primers .......................................................................................................................... 13

Chapter 4: Priming the Charge ............................................................... 15Priming considerations ....................................................................................................................... 15Principles of priming .......................................................................................................................... 15Priming with a detonator ................................................................................................................... 16Priming with detonating cord ............................................................................................................ 17

Chapter 5: Disposal of Explosive Materials ............................................ 19Damage and deterioration .................................................................................................................. 19Disposal procedures ........................................................................................................................... 20

Chapter 6: Legal and Jurisdictional Responsibilities ............................ 21Laws governing explosives ................................................................................................................. 21Canadian laws and regulations .......................................................................................................... 21British Columbia laws and regulations .............................................................................................. 22Local laws ........................................................................................................................................... 23Civil law .............................................................................................................................................. 23

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Chapter 7: Handling Explosive Materials ............................................... 24Factory/vendor/user numbers ............................................................................................................ 24Separation of explosive materials ....................................................................................................... 25Handling procedures .......................................................................................................................... 25

Chapter 8: Transportation of Explosive Materials ................................. 27Labels .................................................................................................................................................. 27Placarding ........................................................................................................................................... 27Transport containers ........................................................................................................................... 28Compatibility ...................................................................................................................................... 28Training and certification of drivers and helpers .............................................................................. 29Documentation ................................................................................................................................... 29Emergency Response Assistance Plan (ERAP) .................................................................................. 30Reporting accidents ............................................................................................................................ 31Fire extinguishers ............................................................................................................................... 31Pre-loading inspection ........................................................................................................................ 32Loading and unloading ...................................................................................................................... 32Rules while in transit .......................................................................................................................... 33

Chapter 9: Storage of Explosive Materials ............................................. 35Storage requirements .......................................................................................................................... 35Magazine design and specifications ................................................................................................... 37Magazine signage ............................................................................................................................... 37Magazine location ............................................................................................................................... 38Magazine protection ........................................................................................................................... 41

Chapter 10: Explosive Materials at the Worksite ................................... 42General requirements ......................................................................................................................... 42Attendant ............................................................................................................................................ 43Container (day box) ............................................................................................................................ 43

Chapter 11: Control of the Blasting Area ................................................ 45Blasting area ....................................................................................................................................... 45Blaster’s authority ............................................................................................................................... 45Assistants............................................................................................................................................ 46

Chapter 12: Drilling Precautions and Requirements .............................. 47Pre-drilling requirements ................................................................................................................... 47Drilling restrictions ............................................................................................................................ 47Socket (old hole) .................................................................................................................................. 47Loaded hole......................................................................................................................................... 48

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Chapter 13: Priming and Placing Explosive Materials ........................... 49Priming ............................................................................................................................................... 49Loading ............................................................................................................................................... 49Pneumatic loading .............................................................................................................................. 50Tamping .............................................................................................................................................. 51Equipment .......................................................................................................................................... 51

Chapter 14: Controlling Fly Material ....................................................... 52Types of fly material ........................................................................................................................... 52Causes of fly material ......................................................................................................................... 52Control techniques ............................................................................................................................. 53

Chapter 15: Securing the Danger Area ................................................... 55Danger area ........................................................................................................................................ 55Clearing the area ................................................................................................................................ 55Guarding charges ............................................................................................................................... 56Placing guards .................................................................................................................................... 56Guard duties ....................................................................................................................................... 57

Chapter 16: Firing the Blast .................................................................... 58Warning signals .................................................................................................................................. 58Blasting signals ................................................................................................................................... 59Blasting log ......................................................................................................................................... 60

Chapter 17: Returning to the Blast Site .................................................. 63Electrical blasting ............................................................................................................................... 63Air contaminants ................................................................................................................................ 63Examining the site .............................................................................................................................. 63Dangers ............................................................................................................................................... 64Loose material .................................................................................................................................... 64Clean up .............................................................................................................................................. 65

Chapter 18: Misfires ................................................................................ 66Types of misfires ................................................................................................................................ 66Causes of misfires .............................................................................................................................. 66Indicators of misfires .......................................................................................................................... 67Minimum waiting times ..................................................................................................................... 68Misfired charge ................................................................................................................................... 68Burning charge ................................................................................................................................... 68Personnel ............................................................................................................................................ 69Removal by hand ................................................................................................................................ 69

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Metallic equipment ............................................................................................................................. 69Identification, destruction, and removal ............................................................................................ 70Drilling to re-fire ................................................................................................................................ 71

Chapter 19: Non-electric Initiation Systems .......................................... 72Safety fuse .......................................................................................................................................... 72Safety fuse assembly .......................................................................................................................... 72Fuse length ......................................................................................................................................... 73Fuse handling ..................................................................................................................................... 73Detonator ............................................................................................................................................ 73Static shunt ......................................................................................................................................... 73Igniter cord connector ........................................................................................................................ 74Igniting the safety fuse assembly ....................................................................................................... 74Acceptable lighting devices ................................................................................................................ 74Determining ignition .......................................................................................................................... 76Hazards and precautions .................................................................................................................... 77

Chapter 20: Detonating Systems ............................................................ 78Detonating cord system ...................................................................................................................... 78Detonating cord .................................................................................................................................. 78Storage and handling.......................................................................................................................... 80Loading procedures ............................................................................................................................ 80Layout patterns ................................................................................................................................... 81MS Connectors ................................................................................................................................... 82Connecting charges ............................................................................................................................ 84Hooking-up procedure ........................................................................................................................ 84Connections ........................................................................................................................................ 85Initiation procedures .......................................................................................................................... 86Safety procedures ............................................................................................................................... 87Shocktube ........................................................................................................................................... 88Shocktube assembly ........................................................................................................................... 88Shocktube detonator ........................................................................................................................... 89Storage and handling.......................................................................................................................... 89Priming and loading ........................................................................................................................... 90Shocktube patterns ............................................................................................................................. 91Hooking up shocktube assemblies ..................................................................................................... 93Interconnected shocktube delay systems ........................................................................................... 94Initiation procedures .......................................................................................................................... 96Safety procedures ............................................................................................................................... 97“Bunch” blasting method ................................................................................................................... 97

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Chapter 21: Electric Initiation Systems ................................................. 99Principles of electrical theory ............................................................................................................. 99Basics of standard electric initiation ................................................................................................ 101Power source ..................................................................................................................................... 101Components of electric initiation systems ....................................................................................... 101Testing a circuit ................................................................................................................................ 105Electrical hazards ............................................................................................................................. 105Electrical storms ............................................................................................................................... 106Static electricity ................................................................................................................................ 106Stray current ..................................................................................................................................... 107Induced current ................................................................................................................................ 107Power transmission lines .................................................................................................................. 108Galvanic current ............................................................................................................................... 108Radio frequency energy .................................................................................................................... 109Standard electric detonator .............................................................................................................. 111Leg wires .......................................................................................................................................... 112Detonator types ................................................................................................................................ 112Circuit configurations ...................................................................................................................... 116Power line blasting ........................................................................................................................... 121Power line calculations ..................................................................................................................... 122Blasting switch .................................................................................................................................. 123

Appendices ........................................................................................... 125Appendix 1: Supplemental Resource References ............................................................................. 126Appendix 2: Glossary of Blasting Terms .......................................................................................... 127Appendix 3: Simple Blast Design ..................................................................................................... 148Appendix 4: Electrical Calculations ................................................................................................. 152Appendix 5: Obsolescent or Limited-Use Explosive Systems .......................................................... 158Appendix 6: Seismic Blasting ........................................................................................................... 162

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Introduction

Blasting and explosives have long been a part of the industrial scene in British Columbia. Over time, they have proven to be a valuable tool used in road construction, fighting forest fires, clearing

snow build-up, and in the search for oil and gas reserves. Yet the use of explosives has left a legacy of serious injury and death. As a consequence, in 1951 the Workers’ Compensation Board was empowered to establish a Blasting Certification Program to ensure that persons engaged in blasting activities had the necessary skills and knowledge to safely handle explosives.

Today, any person who wants to conduct industrial blasting operations (other than on a mine site) must be the holder of a valid blasting certificate issued by WorkSafeBC.

This manual is designed to serve as a study guide for persons who wish to be examined for a WorkSafeBC blasting certificate; it can also be used as a reference for those already working in the industry. Note that illustrations are for explanation only. For specific technical reference, please refer to the product manufacturer's instructions.


Chapter 1: The Theory of Explosives

Blasters are required to have an understanding of the basic theory of explosives and the tools of the blasting trade, including the characteristics, effects, and properties of commercial explosives

and the general criteria for selecting an explosive.

Characteristics

Consider the three characteristics that make an explosive unique:Method of initiation (what sets it off, or initiates the reaction)Composition (what it consists of)Detonation (what happens when it is initiated)

Method of initiation: An explosive is designed to be initiated by the shock effect of a detonator or another explosive. Many products are sensitive to heat, friction, and impact; therefore, they should be protected from effects that could cause premature or accidental detonation.Composition: An explosive is a chemical compound or mixture. An example of a chemical mixture is the black blasting powder used in safety fuse. Most other explosives are mixtures of chemical compounds.Detonation: When an explosive is initiated, a rapid decomposition (explosion) takes place, creating a shock wave with a rapid release of high pressure gases capable of producing destructive effects.

Most commercial explosives are capable of producing gases with temperatures ranging from 1600º C to 3800º C (3000º F to 7000º F) and pressures ranging from 1,379,000 to 103,425,000 kilopascals (200,000 to 1,500,000 psi).

Method Explosive Detonation ofInitiation

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Effects

Detonation of an explosive produces a shock wave and sudden release of heat and gases with four common effects:

Fragmentation of materialDisplacement of materialVibration of groundConcussion (air blast)

In certain applications, explosives are used to create specialized effects. For example, a shaped charge (as in a perforator) is designed to cut or penetrate metal or rock. A special welding technique uses the heat and pressure of the explosive to bond metal pipes together. Some explosives used in pyrotechnic work (special effects) create a flash effect.

Properties

Each commercial explosive has a unique combination of properties. To determine whether or not it is suitable for a specific application, an understanding of its basic properties is necessary. Always refer to the manufacturer’s technical data sheets for proportions and specifications.

Depending on the application, the selection of an explosive should be determined by considering:

Strength (Energy)Velocity of detonation (VOD)DensityWater resistanceFumesSensitivity

Strength (Energy)

Strength is the amount of energy produced by a unit weight or volume of an explosive. It expresses the capacity of an explosive to perform work.

While strength may be a convenient yardstick for comparing various products, there is no recognized standard for measuring strength. The classic measurements based on nitroglycerine (NG) explosives (dynamites) do not accurately reflect the relative energy output of non-NG explosives. Therefore, strength alone may not be a reliable basis for

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Always refer to the manufacturer’s technical data sheets for proportions and specifications.


comparing explosive products. Many blasters compare explosives by the amount of energy in a unit of weight or volume.

The energy produced by an explosive is ultimately determined under actual blasting conditions. Several techniques can be used to obtain a relative comparison and estimate of blast performance.

Velocity of detonation (VOD)

Velocity of detonation is the speed at which the detonation wave travels through a column of explosives. Generally, the VOD increases with a larger diameter, confinement, and temperature in the column. Conversely, a decrease in any of these factors can cause the VOD to decrease.

The VOD of most commercial explosives ranges from 1,500 to 7,500 m (5,000 to 25,000 ft) per second. The shock front will develop radial fracturing in the surrounding material; and faster velocities can produce greater shattering effect and fragmentation of material.

Exploding Column of Explosives

In most applications, a VOD below 2,000 m (6,560 ft) per second may not produce the desired results. In specialty applications, such as secondary blasting (mud capping) and perforating (shape charges), the higher VOD is necessary to produce the desired effect.

Density

Density or “specific gravity” is a measurement of the weight/volume ratio of an explosive. Water has a density of 1. Most explosive materials have densities between 0.6 and 1.7.

Density must be considered when determining the most appropriate borehole charge. Since higher-density products have more explosive in a given volume, they have a greater potential for breakage.

UndisturbedCharge

DirectionofInitiationShockWave

ReactionZone

HotExpandingGases


Water resistance

Water resistance is the ability of an explosive to withstand exposure to water without losing sensitivity or efficiency. The level of resistance depends on the composition of the product, its packaging, and the environmental conditions to which it is subjected.

While some manufacturers describe water resistance in general terms, others identify a specific time period a product may be exposed to water and still detonate. Such descriptions are guidelines only. Water resistance can be significantly affected by water depth and movement, damaged wrappings, and exposure to cold temperatures.

Fumes

Fumes are toxic gases from an explosive detonation. They include carbon monoxide and nitrous oxides. Carbon monoxide (a colourless, odorless gas, lighter than air) tends to rise and has toxic properties. Oxides of nitrogen have an orange/brown colour and tend to hover in the atmosphere. Both gases are poisonous.

In surface blasting operations, fumes quickly disperse to the atmosphere. In confined areas, such as underground workings, exposure to fumes is minimized with low fume explosives and effective ventilation systems.

Sensitivity

Sensitivity is a measurement of the susceptibility of an explosive to initiation by an external force such as a blasting cap, primer, or projectile impact. It is also an indication of the ability of an explosive to propagate detonation initiated by an external force.

Additional properties for consideration in particular applications are the packaging of the explosive and their stability (during handling or long term storage).

In confined areas, such as underground workings, exposure to fumes is minimized with low fume explosives and effective ventilation systems.


General criteria for explosives

Under normal use, explosive products should:Remain intact during the period of storage Not freeze or break down chemically (dissociate) under normal temperaturesBe suitably packaged for the intended useBe safe to handle, transport, and storeRemain sensitive and detonate readily when properly initiatedDetonate properly on initiationPossess the following properties:

Adequate strength for the intended useHigh velocity of detonation (except where shattering is to be avoided)Suitable density for the particular applicationAdequate water resistanceMinimal fumes, particularly in confined areas

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Chapter 2: Classification of Explosives

Dynamites and other high-strength explosives must be treated with caution.

Black blasting powder

Black powder is a low explosive mixture of potassium nitrate, charcoal, and sulphur. It has no water resistance, is sensitive to heat sources and friction, and is highly flammable when dry. Upon initiation, it burns rapidly (deflagrates) with no shock wave, producing a heaving rather than shattering action.

Black powder is used in fireworks, special effect devices, and the (non-shattering) production of marble and slate. In finer grades, it is the core of safety fuse.

Dynamites

Dynamites are explosives containing liquid nitrate esters. The most common nitrate ester used is "NG," which is a mixture of nitroglycerine and nitroglycol. This blend has low freezing properties, is mixed with other ingredients to reduce its sensitivity, and produces a material that can be packed into cartridges. Gelatinizing agents promote water resistance, and antacids promote stability in storage.

Dynamites are cap sensitive and can be initiated by detonators or detonating cord. Most dynamites develop a high VOD that produces a shattering effect.

Dynamites and other high-strength explosives must be treated with caution.

Skin contact with NG or inhalation of NG vapours may cause a “powder headache.”Exposure to moisture and temperatures in excess of 50° C (122° F) cause the composition of dynamites to break down.Accumulations of NG are very sensitive to accidental initiation.Most dynamites can be easily ignited and produce intense heat.When the temperature exceeds 200° C (392° F), dynamite can explode.

All dynamites are in cartridge form, with a paper wrapper that prevents contact with the NG and protects the dynamite from moisture and contaminants. Cartridges are designed to maintain rigidity while being loaded into drill holes and to compress readily when tamped. For applications such as seismic and underwater blasting, cartridges made of heavy paper or plastic tubing are used for greater water resistance and protection from the elements.

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Slurry/watergel explosives

Slurry/watergel explosives do not contain NG. Their explosive base is ammonium nitrate (AN), an oxidizer. Mixed with fuels, metal particles, and sensitizers, it forms an explosive designed to be initiated by a high-strength detonator or a booster. Slurries use gelling agents to provide water resistance. They have high density (1.1-1.5) and can be loaded into wet holes. The high density types usually contain a solid sensitizer, such as smokeless powder, and must be initiated using a booster.

The explosive in slurry/watergel products is suspended in a thickened medium (gel) to protect it from external water. Although many slurry/watergels have lower strengths and VODs than dynamites, they are stable, fire resistant, and highly water resistant.

Emulsions

An emulsion is a dispersion of minute droplets of oxidizer salt solution suspended in oil. The emulsion thus formed is protected against liquid and oil separation by adding emulsifying agents. A bulking medium is also added for density control, in the form of gas bubbles or micro balloons. The more air that is added, the more sensitive but less powerful the blend becomes. Emulsions may also contain solids such as aluminum to enhance power.

Emulsions have varying consistencies, from pumpable liquid to stiff putty. However, a grease-like consistency is the norm. Emulsions are also very water-resistant.

Emulsions are comparatively much safer to handle than other high explosives. There is no possibility of getting NG headaches from touching or smelling an emulsion. At low temperatures, emulsions may lose sensitivity; consult manufacturers' data sheets for use and priming recommendations.

Blasting agents

Blasting agents are composed of Ammonium Nitrate (AN) and contain various other sensitizing fuels such as charcoal, fuel oil, molasses, sawdust, or sugar. They are generally not cap-sensitive.

Emulsions are comparatively much safer to handle than other high explosives.

Blasters' Handbook - �0 -

Blasting agents are relatively inexpensive and, due to their low sensitivity, are stable and safer to store, transport, and use. Most are not water resistant, and moisture exposure can result in poor rock breakage or misfires. Improper on-site mixing can reduce the quality and performance of the product.

A high energy primer is recommended to initiate blasting agents. Improper initiation may result in excessive fumes, poor fragmentation, and misfires.

AN/FO, the most common blasting agent, is a mixture of dry ammonium nitrate (AN) and fuel oil (FO) in a bulk weight ratio of 94% AN to 6% FO. Aluminum granules may be added to the mixture for extra energy. To mix AN/FO, the written approval of the Chief Inspector of Explosives (Explosives Act, Canada) is required.

Blasting agents are either dry (free-running) or slurry. Most dry types, AN or AN/FO mixtures, have no water resistance; therefore, a plastic liner (sock) may be required for wet holes. Dry, free-running products are generally supplied in bulk, or packaged in bags with an oil and water-resistant liner.

Blasting agents and slurry/watergels may be transported in a pumper truck or packaged in various containers.

A high energy primer must be used to initiate blasting agents. Improper initiation may result in excessive fumes, poor fragmentation, and misfires.

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Chapter 3: Initiating Devices and Accessories

Initiating devices

Detonators (blasting caps) produce a powerful shock wave capable of initiating cap-sensitive explosive products. Explosives that are not cap-sensitive will require a cast booster, or be primed with a cartridge of high explosive.

Detonators have a small aluminum shell, closed at one end, into which is pressed a base charge of pentaerythritol tetranitrate (PETN). Except for specialty products, all detonators manufactured in Canada are “high strength” blasting caps.

Most detonators contain a priming charge of lead azide and/or lead styphnate. Both are very sensitive to heat and, when ignited, will reliably initiate the PETN.

Side View of a Safety Fuse Detonator

Safety fuse assembly

The safety fuse assembly consists of a factory assembled blasting cap (detonator), a length of safety fuse, and an igniter cord connector (or other terminating feature).

The igniter cord connector keeps the fuse end dry and allows easy connection to the igniter cord. The connector can be copper or silver in color with a slit in the end. Igniter cord is inserted into the slit and secured by bending the tab to firmly grip the igniter cord. The slit distinguishes the igniter cord connector from the detonator. The detonator is silver and generally marked with the word “explosive.”

BaseCharge

PrimerCharge

IgnitionMixture Shell

SpaceforFuse

IgniterCordConnector

IgniterCord

Fuse

Cap


Shocktube assembly

The shocktube assembly consists of a high strength blasting cap, factory-crimped to a single “shock tube.” This hollow plastic tube is lined with a finely powdered explosive composition.

The shock tube assembly is initiated by a starter device, an electric or non-electric detonator, or detonating cord. The shock wave in the shocktube is capable of detonating the blasting cap.

Plain Shocktube Assembly Showing Detonator and Tubing

Standard electric detonator

Standard electric detonators are available with leg wires in a number of common lengths, with delay times identified on a label attached to them.

Leg wires of electric detonators are “shorted out” with metal foil (a shunt) to protect against premature detonation from stray currents. The shunt also keeps the wire ends clean. Leg wires are folded to minimize kinking and electromagnetic induction, and each bundle is secured with a paper band.

Instantaneous Detonator

Initiating accessories

An initiating accessory is an explosive that assists in detonating a charge by transmitting and/or reinforcing the shock wave from a detonator. Initiating accessories include detonating cords and cast boosters. In certain applications, they may be used as the main charge.

BaseCharge Primer

Charge

PlasticCup BridgeWire&

RubberPlugAssemblyInsulatedLegWires

Anti-StaticGrooveLooseCharge

Shocktube

RubberClosurePlug

DetonatingCordTrunkline

StaticProtection

DelayElement BaseCharge

InitiatingChargeHeatSeal Connector


Detonating cords

Detonating cord has a core of PETN enclosed in a flexible, plastic and textile covering, which provides tensile strength and protection from moisture and abrasion. It is initiated by an electric or non-electric detonator, and explodes at over 6,705 m (22,000 ft) per second. It is capable of initiating other sensitive explosives, including other detonating cords. Detonating cord is available with several “strengths” and grades of protective wrapping.

Boosters and primers

Cast boosters and primers contain high explosive and are initiated by a detonator or detonating cord. They explode with a very high VOD and are use to detonate/initiate explosives in direct contact with them.

Booster

A booster is a manufactured unit of high explosive designed to initiate a non-cap-sensitive charge by boosting/amplifying the shock wave from a detonator or detonating cord.

A cast booster is a cylinder of Pentolite high explosive (a mixture of PETN and TNT). Some boosters have a capwell for holding the detonator. Others have a hollow core through which a detonating cord may be passed.

Cast Primer for Detonating Cord Cast Primer for Blasting Cap

TunnelCapwellTunnel

Blasters' Handbook - �� -

Cartridge primer or “primer”

A cartridge primer is a cartridge of high explosive, such as a stick of dynamite, into which a detonator is placed. It may also refer to a cartridge of high explosive firmly attached to a length of detonating cord, which is in turn initiated by a detonator. Many blasters refer to a cartridge primer simply as a “primer.”

Primer


Chapter 4: Priming the Charge

Priming a charge brings together — for the first time — the explosive and its initiating device. Safe procedures for priming a charge are determined by the conditions, the application, the explosives, and

the initiating device.

Priming considerations

To ensure detonation, the explosive charge must be adequately primed. The velocity of detonation (VOD) of the initiating device must equal or exceed the VOD of the explosives in the main charge. Do not under-prime a charge. This may result in a misfire, improper breakage, and excessive fumes.

Under normal conditions, most high explosives are reliably initiated by a high strength detonator, or detonating cord. Modern dynamites have high sensitivity to initiation, even in cold temperatures. Slurry/watergel/emulsion explosives tend to become insensitive in colder temperatures and may require a “high strength” primer or booster to ensure proper detonation.

Blasting agents have low sensitivity to initiation and require a high strength primer for reliable detonation. If the blasting agent is dry and properly mixed, a dynamite primer or slurry/watergel/emulsion should be adequate. In wet holes, over 50 mm (2 in) diameter, or those containing “deck charges,” a high strength pentolite booster is usually required for each deck.

Be sure to follow the manufacturer’s recommendations when priming an explosive charge.

Principles of priming

The following principles apply to making up and placing a primer:Securely attach the detonator, or detonating cord, to the unit of explosive.Protect the detonator from abrasion, impact, and other harm. If the detonator is placed in the explosive, it should be completely embedded in the centre of the booster or cartridge.It must be possible to place the primer easily and safely, without damage to the detonator, safety fuse, leg wire, tubing, or detonating cord.

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Any explosive contaminated by chemicals or water, or otherwise deteriorated, may be insensitive, and must not be used.

IntheRegulation

Part 21.45 Priming

A primer must not be made up until immediately before placing the explosives.


Position the primer so that the “business” (closed) end of the detonator is oriented toward the main part of the charge. When priming a small diameter hole with a safety fuse assembly, avoid bending or kinking the fuse.

Priming with a detonator

The following procedures apply to making up cast boosters and cartridge primers with a detonator.

Cast booster

Use only:A detonator capable of reliably initiating the boosterA booster with a “capwell” that allows the detonator to be easily and completely inserted

Thread the detonator through the “tunnel”Insert the detonator to the bottom of the capwellEnsure the detonator is securely fastened to the booster by:

Taping any protruding cordline, leg wire, safety fuse, or tubing to the booster, or Tying a half-hitch in the detonator leg wire

Cartridge primer

Use only:A cartridge of good structural integrity, capable of being initiated by the detonatorA “punch” made of wood, plastic, or non-sparking metal such as brass or copper, to form a hole so the detonator can be fully inserted; the hole may be punched in the end or side of the cartridge, but should not exit the other side

Insert the detonator so it is completely buried with the “business” (closed) end oriented toward the bulk of the cartridge; if priming with a safety fuse assembly, avoid bending or kinking the fuseEnsure that the detonator is securely fastened to the cartridge by:

Taping any protruding cordline, leg wire, safety fuse, or tubing to the cartridge, orTying a half-hitch in the leg wires around the middle of the cartridge, if using an electric detonator

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Do not tie a half-hitch in shock tubing.


Side View of a Detonator Affixed to a Cartridge

Priming with detonating cord

The following procedures apply to making up cast boosters and cartridge primers using detonating cord.

Cast booster

Use only:Detonating cord capable of initiating the boosterA booster with a tunnel through which to pass the detonating cord

Pass the detonating cord completely through the tunnelSecure the detonating cord by:

Knotting, to prevent it pulling back through the tunnel, orTaping the cord to the booster

When detonating cord is used, the cord must be attached to the trunkline only at the last, most practicable moment after all holes are loaded.

Side View of a Detonating Cord Affixed to a Booster

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Cartridge primer

Use only:A detonating cord capable of initiating the cartridgeA cartridge of high explosive with the outer wrapping intactA wood, plastic, or non-sparking metal punch, to form a hole completely through the cartridge; a second hole may be required to firmly secure the detonating cord

Pass the detonating cord completely through the holeSecure the detonating cord by:

Knotting the cord to prevent it from pulling back through the hole, orTaping the end of the protruding cord to the side of the cartridge

When detonating cord is used, the cord must be attached to the trunkline only at the last, most practicable moment after all holes are loaded.

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IntheRegulation

Part 21.53 Connecting detonating cord (1) When detonating cords are used, the cords must only be interconnected or attached to trunk cords at the last most practicable moment after all holes are loaded. (2) When detonating cords are used to prime a charge, the cord must be cut from the supply reel before, or as soon as possible after the charge is placed. (3) Detonators or detonator connectors must not be attached to a detonating line until everything is in readiness for the blast.

CartridgePrimer

DetonatingCord

Tape

Knot


Chapter 5: Disposal of Explosive Materials

Any person who owns or possesses explosive materials has a legal responsibility to properly dispose of them. Surplus explosives and detonators in good condition may be returned to a storage facility

or the supplier. Damaged or deteriorated explosives must be destroyed safely.

Explosive materials must not be buried or abandoned. This contravenes the OHS Regulation and is an offence under Section 20 of the Explosives Act (Canada).

Abandoned and buried explosives have caused many accidents. Some may retain their explosive properties for years, even after exposure to cold temperatures and water. With the exception of some blasting agents, burying an explosive, or soaking it in water, will not safely dispose of it.

Damaged or deteriorated explosive materials can be extremely dangerous and must be disposed of by competent persons. Rather than attempting to dispose of a large quantity or an unfamiliar type of product, the blaster should secure the area and obtain the assistance of the manufacturer’s representative or the Explosives Disposal Unit (EDU) of the R.C.M.P.

Every blaster must: Recognize and know the causes of damage and deteriorationUnderstand the dangers involvedUnderstand safe procedures for disposing of the more common types of explosives

Damage and deterioration

Damaged or deteriorated explosive materials and accessories must not be used. Their use can result in accidental detonation, misfires, poor breakage, and excessive fumes. Damage is evident in broken or crushed packaging, outer wrappings of explosives, safety fuse, accessories, and detonator shells. Stained packaging and leaking liquid are other indicators.

Deterioration can result in an alteration of the composition or properties of explosive material. Exposure to moisture and extreme temperatures is the principle cause of deterioration. As well, fuels and solvents can cause chemical breakdown. Some products deteriorate with age, but many retain their composition and properties for several years when stored in a dry, well-ventilated area.

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IntheRegulation

Part 21.39 Abandoned explosives Explosive materials and accessories must not be abandoned, but must be placed in suitable storage or disposed of in accordance with the manufacturer’s instructions.

Damaged or deteriorated explosive materials and accessories must not be used.

Blasters' Handbook - 20 -

If the protective shell or wrapping is damaged or removed, and the product comes in contact with water or chemicals, the deterioration process will be greatly accelerated. Many explosives will become insensitive and not perform as intended. However, detonators and nitroglycerine (NG) explosives that have deteriorated are extremely dangerous to handle or use.

Disposal procedures

A stained explosive may be used only if:It can be safely handled, placed, and usedIt is initiated with a fresh primer, andIt will detonate reliably with the desired effects

Unless otherwise specified by the manufacturer, destruction of damaged or deteriorated explosive materials must be in accordance with the following procedures.

General

Explosive products must be disposed of only by competent persons. If a large quantity exists or there is a safety concern, contact a blaster experienced in this type of work.Clearly identify all damaged or deteriorated products, and keep them separate from serviceable explosive materials.The area in which deteriorated products are stored, handled, or destroyed must be kept clear of hazards and unnecessary persons.Explosive materials must be handled with care to avoid impact and abrasion.

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All damaged, deteriorated explosive materials must be destroyed.

Blasters' Handbook- 2� -

Chapter 6: Legal and Jurisdictional Responsibilities

A blaster is expected to know and comply with all laws governing the handling, possession, storage, transportation, and use of explosive materials. These are detailed in statutes, regulations,

by-laws, and common law. A person who transports, stores, possesses, handles, uses, or destroys explosive materials has legal responsibilities.

Explosive materials fall under several jurisdictions, and some laws may overlap. Compliance with one particular law does not relieve a person from the obligation to comply with other laws and to remain current with any changes in law that may take place.

Laws governing explosives

Following are the federal, provincial, local, and civil laws that govern explosives and blasting.

Canadian laws and regulations

Criminal Code of Canada The Criminal Code of Canada is primarily concerned with criminal activities. Severe penalties are prescribed for negligence and improper possession of explosives. Section 79 states “Every one who has an explosive substance in his possession or under his care or control is under a legal duty to use reasonable care to prevent bodily harm or death to persons or damage to property by that explosive substance." Under Section 82, “Every person who, without lawful excuse, the proof of which lies on the person, makes or has in the possession or under the care or control of the person any explosive substance is guilty of an indictable offence and liable to imprisonment for a term not exceeding five years.”Explosives Act and Explosives Regulations The Explosives Act and Explosives Regulations are concerned with the classification, importation, manufacture, possession, sale, storage, and transportation of explosives. Section 18 of the Explosives Act prohibits trespassing in or about any magazine. Section 20 prescribes severe penalties for anyone who abandons explosives or causes a fire or explosion in or about an explosives magazine or vehicle. The Explosives Act, Explosives Regulations, and Magazine Standards are administered by the Explosives Regulatory Division of Natural Resources Canada. Reports of theft, or enquiries regarding these laws

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A blaster is expected to know and comply with all laws governing the handling, possession, storage, transportation, and use of explosive materials.

Blasters' Handbook - 22 -

and standards, should be directed to the local branch office. Up-to-date information on the Explosives Act and Regulations can be found at: www.nrcan.gc.ca/mms/explosif/index.htm. Transport of Dangerous Goods ActAeronautics Act and Air Regulations, which govern the transportation of explosives by aircraft in CanadaCanada Shipping Act and Dangerous Goods Shipping Regulations, which govern the transportation of explosives by ships in Canadian watersRailway Act and Regulations for the Transportation of Dangerous Goods by Rail, which govern the transportation of explosives by public railway in Canada

British Columbia laws and regulations

Motor Vehicle Act The Motor Vehicle Act applies to all motor vehicles operating on public highways in British Columbia. Section 206 requires that any vehicle transporting explosive materials “must be equipped with not less than 2 fire extinguishers, filled and ready for immediate use, and placed at a convenient point on the vehicle.” The Motor Vehicle Branch administers the Act, and the local police enforce the requirements.Provincial Transport of Dangerous Goods Act This Act invokes the Federal Transport of Dangerous Goods Act, and applies to all intra-provincial explosives transportation. (See Chapter 8: Transportation of Explosive Materials.)Mines Act The Mines Act governs the certification of blasters and storage, transportation, and use of explosives on mining property in British Columbia. The Act is administered by the Ministry of Energy, Mines and Petroleum Resources.Workers Compensation Act The Workers Compensation Act governs the certification of blasters and the handling, storage, transportation, and use of explosives within the inspectional jurisdiction of the Workers’ Compensation Board of British Columbia. The Act and the Occupational Safety and Health Regulation are administered by WorkSafeBC.

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Local laws

Several municipalities and districts in British Columbia have bylaws and regulations that govern the handling, storage, transportation, and use of explosives within their jurisdiction. To obtain a permit required by several local jurisdictions, proof of blasting experience and insurance coverage is often necessary.

Civil law

Civil law governs the relationship between individuals. Any personal injury or damage to property caused by explosive materials may result in a civil suit against the person (blaster) responsible. A fundamental principle of civil law is duty of care. The person responsible for the explosive materials must take all reasonable precautions for the prevention of personal injury or damage to property. Precautions would include adequate guarding and control of fly material. Where explosive materials are involved, the principle of strict liability may be applied. This principle places a greater onus on the person possessing or using explosives, to ensure no personal injury or damage to property results.

The person responsible for the explosive materials must take all reasonable precautions for the prevention of personal injury or damage to property.

Blasters' Handbook - 2� -

Chapter 7: Handling Explosive Materials

Factory/vendor/user numbers

The Explosive Regulations (Canada) require that the outer packaging of an explosive material is permanently marked to identify ownership. On most packaging, there is a printed strip, or an affixed label, used for recording ownership.

Ownership is identified alpha-numerically or numerically, as described in the following chart:

NUMBER IDENTIFICATIONFxxx Factory numberVxxx Vendor numberUxxx User number

The first (left-hand) space of the identification area contains the “F” or factory number of the manufacturer. The next space usually contains the “V” or vendor number of the original seller of the explosive material.

Before releasing any explosives or detonators, the vendor marks the next space with the appropriate identification number of the vendor or user taking possession of the explosive materials. The “U” (user) and the Purchase and Possession numbers identify a person who has purchased explosives for their own use but cannot give away or sell the explosive materials.

A person must be properly identified before taking possession of explosive materials. If the vendor does not know the purchaser, then the person must get clearance from the R.C.M.P. as to identity and character. The identification number of the last vendor or user to possess the explosive materials must be marked on the outer packaging.

If a case of explosives or detonators is opened, it is the responsibility of the person opening the case to mark the inner cartons, packages, or spools with the appropriate identification numbers.


Separation of explosive materials

When explosive materials are handled, transported in a conveyance, stored in a magazine, or kept at a worksite, they must be kept separate from other materials, including drill rods; metal tools; oily rags; and sources of contamination, heat, or impact. Explosives, detonators, and accessories also must be kept separate from each other.

The terms explosives, detonators, and accessories must be clearly understood. Accessories include products that do not explode but that are commonly used to ignite a safety fuse. Most are highly flammable and must be kept separate from both explosives and detonators.

Separation of explosives, detonators, and accessories is outlined in the following chart.

EXPLOSIVES DETONATORS ACCESSORIESBlack powder Plain detonator MatchBlasting agent Electric detonator Igniter cordBooster Detonating connector Hot wire lighterDetonating cord Shocktube detonator Pull wire lighterDynamite Safety fuse assemblySlurry/watergel/emulsion

Handling procedures

An explosive product must be handled in the manner specified by the manufacturer. Special handling instructions are printed on the packaging or contained in the product literature. The following apply to most explosive materials:

Handle detonators and detonating connectors separately from other explosive materialsKeep explosive materials a safe distance from flammable material or open flameDo not drop, throw, or otherwise mishandle any explosive materialsDo not permit any person to keep explosive materials in personal clothingExcept for dry free-running blasting agents, do not remove the protective casing or wrapper from any explosive material

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Explosives, detonators, and accessories must be kept separate from each other.


Stained, damaged, or deteriorated explosive material must be examined by a blaster or other qualified person; if the defect is slight, it may be used but only with new explosive as a primer; if unserviceable, it must be destroyed in a safe mannerDo not abandon explosive material; unused materials must be returned to a container or magazine, or destroyed in a safe mannerExplosives must not be handled during an electrical storm, particularly if thunder or lightning is present; evacuate the site and keep all persons at a safe distance; post guards to prevent entry into the danger area during the storm

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IntheRegulation

Part 21.40 Ignition sources prohibited (1) Smoking is prohibited within 15 m (50 ft) of where explosives are stored, being handled, or are in loaded holes.


Chapter 8: Transportation of Explosive Materials1

Transportation of explosive materials is governed by the Transportation of Dangerous Goods Act (and the Explosives Act and Regulations). Transportation of explosive materials on a worksite is

governed by WorkSafeBC's Occupational Safety and Health Regulation. Further classification and description are given in the Explosives Act and Regulations.

A conveyance transporting explosive materials must be in the exclusive charge of and attended by a competent person. Often, the blaster assumes or is assigned this responsibility, including operating the conveyance. For this reason, a blaster must know the requirements for transporting explosive materials and follow the requirements of the Transportation of Dangerous Goods Act (TDG) and Regulations. The TDG Act categorizes the term “dangerous goods” as being in one of nine defined classes. Explosives are Class 1.

Labels

Labels are small hazard warning signs required to be displayed on one side of any small means of containment (such as, plastic bags, fibre board boxes) of explosives. TDG requirements are to mark the containers with the shipping name and the UN number.

Placarding

The Transportation of Dangerous Goods Act (TDG), the Motor Vehicle Act (B.C.), and the Occupational Safety and Health Regulation require vehicles transporting explosives to display the appropriate large hazard warning placard. The Classification Codes, displayed on these placards, must show:

The class and hazard division of the explosive being transportedThe compatibility letter of the explosive

There are special rules for placarding vehicles transporting mixed loads of explosives with different hazard ratings and/or compatibility groupings (such as, detonators and explosives). The latest TDG Act and Regulations must be checked for current placarding rules. Typically, for allowable mixed loads the appropriate placard to display is the explosives of the lowest division on the vehicle.

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1 Thanks to Transport Canada and Natural Resources Canada — Explosives Regulatory Division for information provided in this chapter.

The latest TDG Act and Regulations must be checked for current placarding rules.


Transport containers

Commercially packaged explosives must be in plastic bags and fibre board boxes that comply with CGSB-43.151 (National Standard of Canada CAN/CGSB-43.151-97, “Packing of Explosives (Class 1) for Transportation,” December 1997, published by the Canadian General Standards Board). United Nations specifications for containers as described in this standard must be used. Typically, if the explosives are in their original packaging from the manufacturer, then non-compliance is rare.

Many conveyances used to transport explosive materials are equipped with fixed compartments or tanks for this purpose. Using an open conveyance, or covering with a tarpaulin, is unacceptable. The part of the conveyance where explosive materials are carried must be fully enclosed, locked, and fire resistant.

A container or compartment must be constructed of or lined with plywood, or similar material, to protect the explosives from abrasion and contact with iron or steel surfaces. Explosive materials must be kept separate from items such as drill rods, metal tools, oily rags, other combustibles, detonators, and other initiating devices.

Explosives and detonators may be transported in the same vehicle provided they are effectively separated by a solid wood partition or a barrier of an approved laminate material at least 150 mm (6 in) thick. The barrier must extend at least 150 mm (6 in) above the highest level to which the explosive materials are packed.

Special precautions must be taken when the conveyance is equipped with a radio transmitter. Electric detonators must be in a closed metal container, electrically bonded to the conveyance, lined with wood or other approved material such as rubber or felt. The leg wires must be kept folded and shunted, and the radio transmitter must be switched off whenever the container is open.

Compatibility

Explosives of the same compatibility grouping may be transported together, provided there is no increase in the probability of an accident, or the magnitude of the effects of such an accident. The Transport of Dangerous Goods Regulations (Part 5.7) contains a compatibility chart indicating which divisions of explosives may be transported together.

Explosive materials must be kept separate from items such as drill rods, metal tools, oily rags, other combustibles, detonators, and other initiating devices.


Training and certification of drivers and helpers

Drivers and persons handling, offering for transport, and transporting explosives must be in possession of a certificate issued by the employer, stating the worker has received adequate training in assigned duties, including knowledge of:

Types of placards, labels, signs, numbers, and other safety marks; what they mean; and when and where to display themA thorough knowledge of the control and emergency features for all handling equipment used in the day-to-day activities of the job Safe practices on the loading, transport, and stowage of dangerous goodsThe proper selection and use of means of containment for dangerous goodsDocumentation for shipping dangerous goods Emergency response assistance planningShipping namesReporting requirements

Self-employed individuals must also determine if they are adequately trained and issue themselves a training certificate.

Employees who are not trained can handle, offer for transport, and transport dangerous goods as long as they are doing so under the direct supervision of a trained person. Training certificates are good for three years, and copies of the training certificates must be kept by the employer.

Documentation

Conveyances transporting explosives must carry a document detailing the quantity and types of explosives being carried. The consignor is responsible for preparing the document, which must be legible and indelibly printed with the following information:

Name/address of place of business of consignor (not a box number)Date document prepared or given to carrier Description of dangerous goods in following order:

Shipping name (such as, EXPLOSIVE, BLASTING, TYPE A)UN Class and compatibility letter (such as, Class 1.1 D)UN number (such as, UNOO81) Packing Group (such as, P.G. II)

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Conveyances transporting explosives must carry a document detailing the quantity and types of explosives being carried.


For each shipping name, the net explosive quantity in International System of Units (such as in kg) Words “24 Hour Number” or abbreviation followed by telephone number with area code for consignor or other competent person who can provide technical information on explosives being carried (must work during transport if not a 24-hour number)Emergency Response Assistance Plan reference number before or after the letters “ERP” or “ERAP” and the telephone number to call to immediately activate the plan

The document must be within reach of the driver or in pocket on the driver’s door while the explosives are in transport, and must be retained for a two-year period by the consignor and carrier.

Emergency Response Assistance Plan (ERAP)

An approved Emergency Response Assistance Plan is required by those that offer for transport or import explosives, using the following rules:

In the TDG Regulation, look up the UN number for each of the explosive products intended to be transported together and determine the quantity for which an ERAP is required (Schedule 1, column 7). If the Net Explosive Quantity of all of the explosives (dangerous good) is greater than the ERAP quantity for any of the specific explosives, an ERAP is required for that load, and placarding is necessary.To register a plan, a complete summary of the plan must be submitted to Transport Canada; contact TDG in New Westminster at 604-666-8771 for more detailed explanations and the process for registration.

An Emergency Response Assistance Plan application is submitted by letter or electronic-mail ([email protected]). The application must contain specific information, including:

A telephone number that will cause immediate activation of the ERAPA description of the emergency response capabilities, including the number of qualified persons available to give technical advice over the telephoneThe number of persons available to advise and assist at the scene

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A list of specialized equipment that is available for use at the emergency siteThe response actions capable of being takenA description of the transportation arrangements to bring the equipment and personnel to the accident siteThe communication systems expected to be used there

Copies of any formal agreements with a third party for assistance to the plan registrant are to be included in the application.

Submit to: Chief, Response Operations (ASDB) 330 Sparks Street Place de Ville, Tower C, 9th floor Ottawa, Ontario, Canada, K1A ON5

If approved by Transport Canada, the plan is given a number that must appear on all shipping documents. A generic example of an ERAP can be found on the TDG website at www.tc.gc.ca/tdg/menu.htm.

Reporting accidents

In the event of an accidental release of explosives, an immediate verbal report is required to be made to the local police and the Provincial Emergency Program at 800-663-3456. The person that has possession of the explosives must also make immediate reports to his or her employer, to the consignor, and the owner of the road vehicle (or lessee or charterer). Any loss, theft, accident, or incident involving explosives must also be reported to the federal Chief Inspector of Explosives.

Fire extinguishers

A conveyance transporting explosive materials in British Columbia must be equipped with at least 2 fire extinguishers. Each must be fully charged, in working order, and readily available for use. The fire extinguishers must be in separate locations on the conveyance, so that at least one is accessible in the event of fire. For less than 2000 kg of explosives, the NFPA (National Fire Protection Association) recommends each must have a rating of 4-A 70-B,C or greater. When a conveyance is operated in freezing temperatures, the extinguishers must be of a non-freezing type.

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If in doubt, report any incident immediately.

IntheRegulation

Part 21.31 Firefighting equipment (1) A conveyance transporting explosives must be equipped with at least 2 fire extinguishers, of a type capable of quickly extinguishing gasoline, oil, or electrical fires.


The extinguishers are intended for putting out fires on or near the conveyance. Do not attempt to extinguish burning explosive materials — most create their own oxygen supply and are not readily extinguished; also impact or shock may cause them to detonate. If the fire is in proximity to explosives or detonators, remove everyone from the “danger area” and keep it guarded until the fire burns out and the area has cooled.

Pre-loading inspection

Before loading explosive materials on a conveyance, an inspection must be conducted to ensure:

The conveyance is in good working order, withBrakes and steering apparatus functioningElectrical wiring insulated and securedChassis and engine clean and free from oil and grease

The conveyance is fully serviced and contains sufficient fuelThe fuel tank and feed lines are in good conditionThe conveyance does not contain flammable materials such as paper, rags, and fuel containersFire extinguishers are fully charged, in working order, and readily available for useContainers for explosive materials have:

No exposed iron or steel on the insideA lid with a suitable lockA secure location in or on the conveyance

Explosives are not to be carried on trailersExplosives are not carried on semi-trailer, unless the semi-trailer is equipped with power brakes operable from the tractor cab, and is attached by fifth wheelTires are not worn smooth, re-grooved, or visibly defective

Unless these pre-loading requirements are satisfied, the conveyance must not to be used to transport explosive materials.

Loading and unloading

A person engaged in transportation of explosive materials must have been instructed in, and must observe, all safety precautions. While materials are being loaded or unloaded, the following precautions must be taken:

Smoking or open flames are not permitted within 15 m (50 ft) of the

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IntheRegulation

Part 21.22 Vehicle operation (1) A vehicle being used to transport explosives must be in sound mechanical condition, suitable for, and capable of, safely transporting explosives. (2) Passengers, other than those assigned to assist in handling explosives, are not permitted on a vehicle transporting explosives.


conveyance, or any loading/unloading operationTurn the ignition OFF and apply the parking brake; if extreme cold and wind conditions might reasonably cause difficulty in restarting the engine, it may be left runningHandle explosive materials in a safe orderly manner; an accidental fall may cause detonationDo not drop, throw, or otherwise mishandle explosive materialsDistribute the load evenly between the load-bearing axles of the conveyanceDo not load in excess of 80% of the vehicle’s rated capacity, commonly known as Gross Vehicle Weight (GVW), except as permitted by the Explosives Regulations.

Rules while in transit

The authorized operator must:Have a valid driver’s licenceBe at least 18 years of ageHave been instructed and proven competent in transportation of explosive materialsPossess documentation required by the Explosives Regulations (Canada) and the TDG Regulations

Only the driver and persons assigned to assist in handling explosives are permitted on a vehicle transporting explosivesA conveyance or mobile equipment containing explosive materials must be attended by a competent person at all timesOnly refuel a conveyance carrying explosive materials when the ignition is shut off, and in a location where danger to the safety of workers or the public is minimizedWhen operating a motor vehicle:

Drive in a manner consistent with road, traffic, and weather conditionsAvoid populated areas whenever possibleDo not drive in proximity to a fire unless safe to do so

When approaching a railway crossing:With an automatic signal device, reduce the vehicle’s speed and ensure that the crossing is safe before proceedingWithout an automatic signal device, bring the vehicle to a complete stop and proceed only when the way is clear

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Before crossing any main highway, bring the vehicle to a complete stop and proceed only when the way is clear and safeWhen parked overnight, the vehicle:

Must be attended by a competent person not under 18 years of ageMust not be parked in an area likely to give rise to fire or explosion, near habitation, or near a building containing flammable materials

If the conveyance breaks down:Make minor repairs or permit minor repairs only if they can be done safelyAllow major repairs only when the explosive materials have been transferred to another vehicle or a place at least 300 m (985 ft) from any inhabited premises, and placed under proper securityNotify the Chief Inspector of Explosives; it is recommended the local police be contacted in the event of an accident, or break down, of a conveyance transporting explosive materials

Report an accident involving the conveyance, or any suspected, attempted, or actual theft of explosive materials:

Immediately to the nearest police detachmentIn writing to the Chief Inspector of Explosives, stating:

Place, date, and timeThe conveyance/magazine licence numberThe identification number, quantity, and type of explosive materials involvedDetails of the accident or theft

If a vehicle contains explosive materials in excess of 2000 kg (4400 lb), the Explosives Regulations (Canada) impose additional requirements:

The licenced driver must be 21 years of age or overThe vehicle must be equipped with at least two (2) fire extinguishers having a rating of 10 BC or greaterA copy of the Explosives Transportation Permit must be carried in the vehicle

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IntheRegulation

Part 21.22 Overnight parking (1) When a vehicle carrying or containing explosives is to be parked overnight, the premises in which the vehicle will be parked must not be used for any other purpose which may involve any substance likely to cause explosion or fire. (2) Such premises must be away from habitation and buildings that contain flammable materials.


Chapter 9: Storage of Explosive Materials2

Storage of explosive materials is governed by the Natural Resources Canada — Explosives Regulations. These regulations, and the Magazine Standards, stipulate requirements for magazines and

storage within them. Up-to-date information can be found at: www.nrcan.gc.ca/mms/explosif/index.htm.

“Keeping” or holding explosive materials at a jobsite during normal working hours is governed by WorkSafeBC's Occupational Health and Safety Regulation. These requirements are covered in Chapter 10.

Neither WorkSafeBC nor Natural Resources Canada regulations require a certified blaster to be responsible for storage. Often a blaster assumes or is assigned this responsibility. In this case, the blaster is expected to know the basic requirements for storing explosive materials.

Storage requirements

Explosive materials must be stored in a safe, secure facility to protect them from theft, damage, and contamination.

A licenced facility is a magazine for which a licence has been issued by the Explosives Branch of the Department of Energy, Mines & Resources (Canada). There are two types of licenced facilities:

A Licenced Vendor Magazine, from which a vendor is authorized to sell or distribute explosive materialsA Licenced User Magazine, usually under the control of a blaster, in which a user is authorized to store explosive materials for use in a blasting operation

The terms under which the licence is issued will specify the location, maintenance, operation, safeguards, and permitted contents of the magazine. These terms must be strictly adhered to, and the licensee must:

Prohibit entry by unauthorized personsProhibit iron or steel tools, matches, or flammable materialsKeep the interior clean and free of gritMonitor the behaviour of persons in or near the facilityEnsure magazine key securityMonitor the facility to ensure explosives are secure Report theft to the Explosives Regulatory DivisionUpgrade security as required

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2 Thanks to Transport Canada and Natural Resources Canada — Explosives Regulatory Division for information provided in this chapter.

Explosive materials must be stored in a safe, secure facility to protect them from theft, damage, and contamination.


The operator of a licenced explosives storage facility is required to maintain a record of the explosives stored. This record is known as the “Magazine Log Book.” The operator must record information of any explosive material that is received or issued, including:

The strength and quantity of each typeThe brand nameThe cartridge sizeThe date received and issuedThe name and address of the supplierThe intended use of the material

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Sample Magazine Log for Explosives

MAGAZINE NO.: __________________________________ EXPLOSIVE LIMIT: _______________________________

SUPPLIER: _______________________________________ ADDRESS: _______________________________________

DateBrandName,Strength

&CartridgeSizeStock/Quantity

Use SignatureIn Out Balance


Sample Magazine Log for Detonators

MAGAZINE NO.: __________________________________ EXPLOSIVE LIMIT: _______________________________

SUPPLIER: _______________________________________ ADDRESS: _______________________________________

Date Type __________________ Length______________________ Use SignatureDelay/Period

The magazine log must be kept up to date and retained for three years from the date of the last entry.

Magazine design and specifications

The standards for magazine construction change regularly as security requirements increase. Construction details and specifications can be found in the Explosives Regulatory Division publication Storage Standards for Industrial Explosives. Up-to-date information can be found at: www.nrcan.gc.ca/mms/explosif/index/htm.

Magazine signage

A site where explosive materials are kept or stored must be suitably identified by warning signs. They must be conspicuous, but should not attract undue attention. An Explosives Inspector (Canada) may stipulate the placement and wording of warning signs.


The normal access routes should be posted with signs displaying wording similar to the following:

EXPLOSIVESDANGER

KEEP OUT

DANGER — EXPLOSIVESNO TRESPASSING

PENALTY — SECTION 18CANADA EXPLOSIVES ACT

NO SMOKING — NO MATCHES

Signs should be placed at D7 distance from the magazine (see following table), but may be closer if doing so would draw undue attention to the site.

Magazine location

A site where explosive materials are kept or stored must be located a safe distance from any road, building, or place frequented by people. The minimum distance a storage facility must be located from such areas depends upon the quantity of explosive materials.

Table 1: Quantity-Distance for Explosive Materials gives minimum distances in metres, which may be adjusted at the discretion of an Inspector of Explosives. It is recommended that greater distances be selected whenever possible.

Locate the storage site at the base of a high bank or in a grove of trees. This will:

Hide it from viewReduce the likelihood of lightning strikesProtect buildings and people in the event of accidental explosion

Placing a container or magazine on the north or north-east side of a tree will provide shade in the hot summer months.

Keep explosive materials a safe distance from electrical transmission lines — at least the spacing between the poles or towers. For example, if the distance between poles is 60 m (198 ft), explosive materials must not come within 60 m (198 ft) of the lines.

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A site where explosive materials are kept or stored must be located a safe distance from any building or place frequented by people.


Table 1: Quantity-Distance for Explosive Materials (TDG classes 1.1 and 1.5)

NetExplosiveQty(kg)

D2Distance

betweencaps&powder(metres)

D4Lightlytravelledroad

(metres)

D5Roadsand

streets(metres)

D6Factory(metres)

D7Residence(metres)

D8Highrise/School/Hospital(metres)

50 10 30 180 45 270 40060 10 32 4570 10 33 4680 11 35 4890 11 36 50

100 12 36 53120 12 40 55140 13 42 60160 14 44 63180 14 46 65200 15 47 65250 16 51 70300 17 54 75350 17 57 80400 18 59 83450 19 62 88500 20 64 90600 21 68 95700 22 72 100 400800 23 75 105 415900 24 78 108 430

1000 24 80 113 4451200 26 86 120 4751400 27 90 125 5001600 29 94 130 5201800 30 98 135 5402000 31 105 180 140 270 560


NetExplosiveQty(kg)

D2Distance

betweencaps&powder(metres)

D4Lightlytravelledroad

(metres)

D5Roadsand

streets(metres)

D6Factory(metres)

D7Residence(metres)

D8Highrise/School/Hospital(metres)

2500 33 110 185 153 275 6103000 35 120 205 163 305 6403500 37 125 220 170 330 6804000 39 130 235 178 350 7105000 42 140 255 190 380 7606000 44 150 270 203 405 8107000 46 155 285 213 425 8508000 48 160 300 223 445 6909000 50 170 310 235 465 930

10000 52 175 320 240 480 96012000 55 185 340 255 510 102014000 58 195 360 270 540 108016000 61 205 375 280 560 112018000 63 210 390 295 590 118020000 66 220 405 305 610 122025000 71 235 435 325 650 130030000 75 250 460 345 690 138035000 79 265 485 365 730 146040000 83 275 510 380 760 152050000 89 295 550 410 820 164060000 94 315 580 435 870 174070000 99 330 610 460 920 184080000 105 345 640 480 960 192090000 110 360 670 500 1000 2000


Magazine protection

Explosive materials must be protected from fire and lightning. To prevent fire, keep the area within 8 m (26 ft) of a storage area or facility clear of dry grass and other combustible materials. Take precautions to ensure matches, smoking, and naked flames are kept out of this area. If a fire occurs near a storage facility, evacuate all personnel, and keep a safe distance from the fire, as indicated in column D8 of Table 1. Never attempt to extinguish burning explosive materials. On the approach of and during a thunder storm, close all storage facilities and keep a safe distance from explosive materials.

Never attempt to extinguish burning explosive materials.


Chapter 10: Explosive Materials at the Worksite

General requirements

Explosive materials must be kept separate from flammable accessories such as igniter cord, matches, and fuse lighters. They must be kept separate from detonators and detonating connectors until the last practicable moment before they are brought together for the blast.

All explosive materials delivered to a worksite must be kept in a safe location:

At least 7.5 m (25 ft) from flammable materialA safe distance from mobile equipmentProtected from falling rocks and other unstable materialIn conformity with the minimum safe distances specified in Table 1: Quantity-Distance for Explosive Materials.

2. At the worksite, explosive materials must be guarded by a competent person or kept in a locked, secured container until returned to a licenced magazine.

Explosive materials should be in a suitable container, even when attended, to protect them from contamination, damage, or accidental detonation.

Explosives, particularly dynamites, should be kept in their original containers with the plastic liner intact.

3. If explosive materials are kept on a conveyance or drilling rig, at the worksite, they must be:

Kept in locked containers, orAttended by a competent person

The container protects them from contamination, damage, or being lost. After working hours all explosive materials must be returned to a licenced magazine or stored in accordance with the Explosives Act (Canada).

1.

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Explosive materials must be kept separate from flammable accessories such as igniter cord, matches, and fuse lighters.


Attendant

Whenever explosive materials are attended by a competent person, that person must:

Be authorized by the employer, supervisor, or blasterBe mentally and physically capable of guarding the materials Maintain visual contact with and control access to the materials

Container (day box)

On a work site, containers for keeping explosive materials must be:Fully enclosedLockedSecure

Most containers are metal or metal reinforced wooden boxes, with a door or lid secured by a heavy duty padlock. Such containers are known as “day boxes.”

Acceptable padlocks are listed in Storage Standards for Industrial Explosives published by the Explosives Regulatory Division of Natural Resources Canada.

An explosive materials container must be properly constructed, maintained, and identified. The interior must have no exposed iron, steel, or other hard, gritty material. It must be kept clean and dry, and the word “EXPLOSIVES” must be conspicuously marked on the exterior.

Typical “EXPLOSIVES” Day Box Container Typical “DETONATOR” Box

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Day boxes must be kept locked when unattended.

IntheRegulation

Part 21.16 Detonators (2) At the loading site, detonator products must be stored separately from other explosives, and in a crush resistant box which is clearly identified.


At the loading site, detonators must be kept in a crush-resistant portable container capable of protecting the detonators from damage. The container is usually made of plywood with a hinged or sliding lid marked with the word “DETONATORS.” Since it is attended by a blaster or an assistant, a lock is not required.


A blasting operation involves “use” of explosive materials, which includes preparing, placing, and firing a charge; handling a misfire; and destroying explosive materials.

Every blasting operation must be conducted or directed by a certified blaster who controls and is responsible for all aspects of the work. The blaster’s authority covers all assistants, workers, and equipment in the area surrounding the operation. This is known as the “blasting area.”

Blasting area

A blasting area extends at least 50 metres (165 ft) in all directions from any place in which explosive materials are being prepared or placed, or where an unexploded charge is known or believed to exist. This minimum distance should be increased according to site conditions and the quantity of explosives being used. Table 1: Quantity-Distance for Explosive Materials should be used to determine the size of the blasting area.

Furthermore, if an activity or condition outside the blasting area endangers any person engaged in the operation, the blaster must take corrective action. The safety of every person within the blasting area is a primary responsibility for blasters.

Note: The blasting area is an “administrative” area. When the blast is fired, the actual danger area may be far greater. (See Chapter 16 for more information on a blaster’s responsibility to secure the danger area.)

Blaster’s authority

To avoid conflict when more than one certified blaster is involved in a blasting operation, the employer is required to designate one blaster as the “Blaster of Record,” who is responsible for conducting or directing the use of explosive materials on that site. The blaster of record must have authority to safely conduct and direct activities within the blasting area. The employer and supervisors must support the blaster in exercising this authority.

Neither the employer nor a supervisor should interfere with the blaster responsible for a blasting operation. However, if the employer believes that the blaster has failed to comply with any of the blasting requirements in the Occupational Health and Safety Regulation, manufacturer’s

IntheRegulation

Part 21.5 Authority to blast

(2) All work within the blasting area must be done under the authorization of the designated blaster of record responsible for that area.

Chapter 11: Control of the Blasting Area


recommendations, or recognized safe blasting practices, the employer must immediately investigate the incident and may suspend the blaster from performing the duties of a blaster.

The blaster conducting or directing an operation must have a valid blaster’s certificate issued by WorkSafeBC. This specifies the type of blasting the blaster is qualified to conduct or direct. The employer is required to record and verify details of the blaster’s certification, including:

Name and addressCertificate numberCertification codesAll conditions/restrictionsThe expiry date

For more information on blaster certification, contact the nearest WorkSafeBC office (see the list at the end of this book).

Most employers retain a copy of the blaster’s certificate. The original must be kept by the blaster; and whenever the blaster conducts or directs a blasting operation, the certificate must be readily available at the worksite, to be produced on request of an officer of WorkSafeBC.

Assistants

Only competent persons are permitted to assist a blaster, and then only if they have demonstrated a knowledge of safe work procedures. The blaster is responsible for the assistant and any work done by the assistant.

When an assistant is unfamiliar with a task, the blaster is expected to provide training and exercise continuous visual supervision. An assistant must not conduct a blasting operation unless the blaster directing the work is physically present in the blasting area.

Whenever the blaster leaves the blasting area, the assistants must guard the explosive materials and wait until the blaster returns before continuing the operation.

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IntheRegulation

Part 21.5 Authority to blast

(3) A blaster may be assisted by persons who do not hold blaster’s certificates, but the blaster must have authority over the assistants and must exercise visual supervision over them and be responsible for their work during explosive loading, priming, fixing or firing.


IntheRegulation

Part 21.42 Predrilling requirements

Before drilling begins (a) in a previously blasted area, the surface to be drilled must be exposed and examined for misfired explosives, (b) faces or slopes must be cleared of loose material, or otherwise stabilized to prevent slides or falls of rock, and (c) the location of utility services must be determined and clearly marked.

Chapter 12: Drilling Precautions and Requirements

A blaster is expected to know and understand the precautions and requirements for drilling where explosives are being used. Drilling into rock or other hard materials is an activity that, if

unsupervised, could result in an accident.

Pre-drilling requirements

Before drilling commences, the blaster must survey the site and surrounding area to determine the stability of rock faces, and whether the area has been blasted before. The muck pile may have to be excavated by machinery to stabilize the material and expose previous drill holes. The blaster must inspect for misfired holes or evidence of explosive materials such as protruding wires or cartridges. Old drill holes (sockets) or remnants of drill holes should be examined and clearly marked for identification during subsequent drilling operations.

Misfired holes or holes containing unexploded explosives are dangerous and must be dealt with before other regular work can be carried out. Disposal procedures for explosive materials are covered in Chapter 5 and Chapter 18.

Drilling restrictions

Drilling into explosives can cause an explosion. When drilling operations take place in an area where previous blasting has been carried out, the requirements of the Occupational Safety and Health Regulation must be complied with.

Socket (old hole)

Although the driller may believe an old hole to be explosive free, this requirement is intended to prevent any contact with explosives.


Loaded hole

In most operations, it is unnecessary to drill in proximity to loaded holes or to load near drilling operations.

Collapsing drill holes, or drilling and loading underwater, may require a variance to the application of this Regulation. If granted, the blaster must direct the angle and depth of the holes being drilled to ensure no contact is made with explosives in adjacent loaded holes. A tamping rod placed in the collar of the loaded hole may assist in determining the correct angle for the new hole.

IntheRegulation

Part 21.43 Drilling prohibitions

Drilling must not take place within (a) 15 cm (6 in) of any part of a bootleg, or (b) 6 m (20 ft) of any part of a hole containing explosives, unless prior written permission has been obtained from the Board.


Chapter 13: Priming and Placing Explosive Materials

Blasting operations involve making up and placing explosive charges. Making up a charge with an initiating device is known as “priming.” “Placing” a charge involves loading it into a bore hole

or otherwise positioning it to be detonated. A blaster is expected to know the procedures, requirements, and restrictions for priming and placing explosive charges, in any situation.

Priming

The procedures for making up primers are described in Chapter 4. The following is concerned solely with priming restrictions.

A primer with an initiating device must not be made up until immediately before the charge is placed. To ensure the safety of workers and others, the period of time an initiating device is attached or connected to an explosive should be minimized. In special applications, where it is necessary to make up primers in advance, a variance must first be obtained from WorkSafeBC.

Only a non-sparking tool should be used to make a hole in an explosive cartridge.

Loading

Drilled holes must be examined to ensure they are clear of obstructions that could hinder loading the explosive. In unstable ground, or underwater, where drill holes may collapse, special techniques employing tubular inserts are used to keep the holes open.

Techniques for removing mud and rocks from a hole include:Removing the obstruction using a “scraper” (copper rod with a dished end)Blowing out the mud and rock with a blow pipe using compressed airPushing the obstruction to the bottom of the hole with a tamping rod or loading pole

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A primer with an initiating device must not be made up until immediately before the charge is placed.


Copper Scraper Blow Pipe Loading Pole

A hole may be completely blocked, particularly if it intersects a slip or fault. It may be necessary to redrill the hole, taking into consideration the drilling restrictions for adjacent loaded holes discussed in Chapter 12.

Explosive materials must not be loaded into a hole that is hot from drilling operations or a previous blast. A “hot hole” with a temperature in excess of 65° C (150° F) may cause many types of detonators and explosives to detonate prematurely.

Pneumatic loading

Pneumatic loading uses compressed air to place explosive materials into a drilled hole; it requires a pneumatic loading machine and a special hose.

When pneumatically loading a blasting agent (such as, ammonium nitrate fuel oil — ANFO), use only semi-conductive hose designed for this purpose. This will drain static electricity (a cause of accidental detonation), which may be produced by the flow of the blasting agent through the hose.

During the loading operation, the pneumatic loading machine must be effectively grounded by connecting it to a metal stake driven into the ground or rock surface. The grounding cable must not be attached to rails, pipes, or other conductors, which could introduce stray electric charges from distant sources such as lightning.

Electric detonators, and hole liners with any type of detonator, must not be placed in a hole prior to it being loaded pneumatically, unless written permission has first been obtained from WorkSafeBC. Liners are usually plastic and can contribute to the buildup of static electricity during loading.

Explosive materials must not be loaded into a hole that is hot from drilling operations or a previous blast.

IntheRegulation

Part 21.55 Pneumatic loading

(1) Explosives may only be loaded pneumatically if the procedures and equipment used will prevent buildup of static electricity or hazards from stray electric currents. (2) Prior written permission of the Board must be obtained before any pneumatic loading is carried out at a hole which contains an electric detonator.


Bore Hole Charger

Tamping

For an effective blast, explosive materials may be compressed into a bore hole with a tamping rod. This will ensure explosive continuity. Tamping rods should be made of wood or plastic and have non-sparking metal fittings. Devices made of iron or steel must not be used.

Successful tamping requires steady pressure. Excessive force or impact could damage the explosive materials or cause premature detonation. Undue pressure on a primer attached to a detonator can result in accidental explosion.

In an “up hole,” cartridges can be held in place by means of a plastic “shuttlecock,” inserted with the points gripping the sidewalls to prevent withdrawal.

Equipment

Equipment and vehicles not required in the blasting operation must be kept out of the blasting area. Mobile equipment is only permitted in proximity to explosive materials when under the direct control of the blaster in charge and only to assist the blaster in:

ExcavatingPlacing fill/stemming materialPlacing blasting mats

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AirIn

Semi-ConductiveHose

Screen

ANFOHopper

ANFO

Borehole

Undue pressure on a primer attached to a detonator can result in accidental explosion.

A primer cartridge should not be tamped directly.


Chapter 14: Controlling Fly Material

Fly material is the undesirable throw of debris from an explosion. High pressure gases are capable of propelling materials a considerable distance with great force. Fly material can cause

serious injury and property damage.

All blasting operations are capable of producing fly material. The blaster should know the causes and the techniques necessary for controlling it; the blaster is responsible for the protecting people and property from fly material.

Types of fly material

Fly material is any material (such as, gravel, brick, earth, metal, and wood) disturbed by the blast, the most common of which is known as “fly rock.”

Causes of fly material

There are many causes of fly rock:Geological seams, planes, and cracks that cause the rock to break unevenlyGeological cavities that collect an excessive amount of explosives Poor pattern design, with the burden and spacing too close (i.e., excessive powder factor)Improper distribution of explosives in the rockShallow or “crater” blasting without containmentExplosives that have excessive strength or velocity of detonationBoreholes that have been overloadedImproper delay timing that does not provide adequate burden reliefCollar priming, which can create greater throw than bottom (toe) primingFailure to use covering material, blast mats, or sand to contain the fly materialsInadequate or insufficient stemming

To summarize, fly rock can occur if:The rock is abnormalThe drill pattern is inaccurateExcess explosives are loadedThe sequence of initiation is improperEffective containment (such as blast mats) are not used

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Fly material can cause serious injury and property damage.


Control techniques

To effectively control fly material, the blaster must:Assess the material to be blasted. Do geological faults exist? Is the material soft or brittle? An experienced blaster should be able to reasonably determine the nature of the material.Determine the nature of the material to be drilled. Drilling the material should reveal its nature and the location of any abnormalities (e.g., slips, cavities). If there is doubt as to the effect of the explosives on the material, a small test blast should be conducted first.Select the most appropriate drill pattern. This is usually determined by the type of material (rock) and the diameter of the drill bit. The blast design should have burden and spacing that is neither excessive nor too tight. Drill hole alignments must be accurate.Choose the most suitable explosive for the conditions with an energy factor that is adequate but not excessive.Properly load each hole. Should a cavity, fault, or slip exist, load accordingly. Beware of cavities, and do not overload a hole. Ensure the hole is properly stemmed. The depth of stemming is generally between 0.7 and 1.0 times the burden distance. Ideally, the stemming material is well-graded, crushed rock.Choose the most suitable initiation system. Delay sequence blasting must allow for adequate burden relief. Generally, bottom (toe) priming does not create as much “throw” as top (collar) initiation, and is not as likely to result in a cutoff hole.Where necessary, cover the blast with a layer of sand or other fill material. In residential areas, cover material should be at least 1 m (3 ft) in thickness.When necessary, use blasting mats to contain fly material.Mats can be constructed of logs, mesh, and rubber tires, leaving small gaps to retain debris with a diameter in excess of 50 mm (2 in) but allow the escape of explosive gases. Solid coverings (such as steel plate) can be projected by the expanding gases and must not be used.Inspect blastmats before placement. Remove embedded rock or possible fly material.

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IntheRegulation

Part 21.66 Blaster’s responsibility (1) The blaster must take precautions for the protection of persons and property, including proper loading and stemming of holes, and where necessary, the use of cover for the blast or other effective means of controlling the blast or resultant flying material.


Blasting Mats

Covering a blast with fill material and blasting mats is at times impractical. To protect property from damage, it may be more effective to place a substantial guard or covering material directly over the object requiring protection.


Chapter 15: Securing the Danger Area

The most critical period in a blasting operation is the time of the blast, when there is the greatest potential for damage and serious injury.

To prevent accidents from detonation of an explosive, the area surrounding a blast must be under the control of a certified blaster, responsible for the safety of persons who could be affected. Additionally, this danger area must be guarded to prevent entry during the time of the blast.

Danger area

The “danger area” is an area centred on the explosion, in which a person could suffer injury from the effects of the blast, including:

Air blast (concussion)FireFly materialGround vibrationA mud or snow slide

A danger area exists at the time of a blast, the size of which is determined by the:

Amount of explosives usedTechnique of blastingType of material blasted

Clearing the area

During priming, placing, and connecting charges, only the blaster and blaster’s assistant(s) should remain in the area. No other person is allowed entry unless the blaster gives permission, and maintains control over that person’s activities.

Before detonating a charge, the blaster must clear the danger area of all persons. Where visibility is obstructed, the blaster must conduct a thorough examination to ensure no one is present.

Before sounding the warning signals and firing the blast, the danger area must be cleared by the blaster or blaster’s assistant. Sounding the warning signal does not relieve the blaster of the responsibility to clear the area, and to keep it clear during the blast.

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The blaster is responsible for establishing the limits of the danger area.


Guarding charges

An explosive charge must be guarded at all times by a competent person from the time it is placed until the time it is detonated. A person assigned to guard an explosive charge must be properly instructed in safety and security.

A guard must:Protect the charge from damage or accidental detonationPrevent deliberate tampering with or theft of any part of an explosive charge

It is usual practice for a member of the blasting crew to guard an explosive charge until it is detonated. If it cannot be detonated in normal working hours, it will be necessary to post a guard overnight.

The guard should be provided with suitable equipment, including lights and signs. If equipped with a radio, the guard must maintain a safe distance from any electric detonators.

Placing guards

The blaster is responsible for posting “guards” to prevent access to the danger area. Warning signs, barricades, or other obstructions cannot substitute for a guard. The guard must be posted in a safe location, usually outside the danger area.

All access to the danger area must be effectively guarded. In a small operation where visibility is unobstructed and the initiation system is instantaneous (electric blasting), it may be possible for one person to guard the danger area.

Acceptable Not Acceptable

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IntheRegulation

Part 21.66 Blaster’s responsibility (3) The blaster must post workers who have the sole responsibility of guarding against entry into the danger area of the blast site, and the workers must be instructed as to their duties and responsibilities. (4) Whistles, signs or other signals may not be used in place of the guards required by subsection (3). (5) Before sounding the warning signals, the blaster must clear the danger area and post guards as required by subsections (2) to (4), and must ensure that all persons have reached a place of safety.


Where visibility is restricted, or the initiation system is non-instantaneous, more than one guard will be required. If there is delay between the initiation and detonation of the charge, as in safety fuse blasting, there is a much greater need for effective guarding.

If the blast could pose a hazard to aircraft, special precautions must be taken. It is recommended that a “Notice to Airmen” (NOTAM) warning of the blasting operation be issued to pilots.

To request a NOTAM, contact the nearest flight service station at least 24 hours before the scheduled time of blasting. Do not assume the NOTAM has been received and understood by all pilots in the area.

When blasting near a highway or populated area, it may be difficult to control public access. The assistance of the local police may be necessary to barricade streets or evacuate buildings.

Guards should be provided with appropriate equipment. For example, the guard will require a flagger’s vest and a “STOP” paddle to control traffic.

Guard duties

Only competent persons should be assigned to guard a danger area. They must be mature individuals capable of performing guard duties.

The blaster is responsible for instructing all guards on their duties and responsibilities, including:

The location of the guard postWarning devices and signalsPreventing persons from entering the danger areaWatching for fly materialPreventing re-entry to the danger area until

The all clear signal is given, orThe guard is personally relieved by the blaster

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Only competent persons should be assigned to guard a danger area.


Chapter 16: Firing the Blast

Before firing a charge, the blaster must:Make a visual inspection of the blasting circuit or tie-in to ensure all connections are secure and the blast can be safety detonatedConfirm that any surplus explosive materials have been removed to a safe placeDetermine that adequate protective measures have been taken for the safety of persons and protection of propertyVerify that the danger area is clear and the necessary guards are at their posts

The purpose of visually inspecting the blasting circuit or tie-in is to ensure all connections are properly made and intact, all the charges have been connected, the circuit is undamaged, and the blast can be safely detonated.

All loaded holes in a blasting area must be detonated:In one blasting operation, orIn a manner that minimizes the possibility of misfires, damage to other charges, or burying other charges

The blaster must ensure surplus explosives and detonators have been moved to a safe place. A container or magazine must be located outside the danger area.

When blasting in proximity to trees, precautions must be taken to prevent broken tops and limbs, hangups, leaners, and other similar hazards.

Before sounding the warning signals, the blaster must make a final check that the danger area is clear, and each guard is at his or her post.

Warning signals

Every person in the vicinity of a blast should understand the warning signals. These warn that a blast is about to be fired.

Before any charge is fired, the blaster must:Ensure that every person in the danger area understands the warning signals, orPost the signal code at conspicuous locations in the danger area

Devices for sounding warning signals must be:Distinct from other signal devices in the area, ANDAudible throughout the danger area

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The blaster must ensure surplus explosives and detonators have been moved to a safe place.

IntheRegulation

21.68 Firing all holes (1) Charges must be fired in logical sequence. (2) If any detonation could affect other charges placed nearby, all of the charges must be fired in one operation.


A compressed air horn, or a horn device attached to a compressor or air hose, is commonly used. A standard car or truck horn is not distinct and is therefore unacceptable as a warning signal device.

Compressed Air Horn

The standard warning signal is 12 short signals at one-second intervals, followed by a two-minute wait before detonating the explosive charge. Sounding the warning signals does not relieve the blaster of the responsibility to clear the danger area and keep it clear during the blast.

Blasting signals

Before the blast, give twelve short signals at one-second intervalsWait two (2) minutesFire the blast

During the time between the warning signals and the “all-clear” signal, only the blaster responsible and persons authorized by the blaster may enter or remain in the blast area.

After a blast, it may be necessary for the blaster to clear dangers before the “all-clear” signal is sounded.

Following the blast and after the area has been inspected and found safe, one prolonged whistle signal of at least 5 seconds duration must be sounded to signal that permission is granted to return to the blasting area.

Note: The standard warning signals are not required in underground work. Also, in avalanche control work, alternate closure and warning signals may be approved.

•••

IntheRegulation

Part 21.69 Blasting signals

(1) The blaster must ensure that an audible signalling device, distinct from other signalling devices in the area, is used to give the following warning signals: (a) preceding the blast, 12 short whistle signals must be sounded at one second intervals; (b) two minutes must elapse after the last warning signal before initiating the blast; (c) following the blast and after the area has been inspected and found safe, one prolonged whistle signal of at least 5 seconds duration must be sounded, to signify that permission is granted to return to the blasting area. (2) Subsection (1) does not apply to avalanche control, single underground headings, buried seismic work in isolated locations or other circumstances deemed appropriate by the Board, in which case the blaster must ensure that alternative warning procedures acceptable to the Board are used.


Blasting log

Blasters must keep a record of preblast loading data and of the examination of the site after the blast. This blasting log should not be confused with the magazine log book.

The blaster is required to record certain information in the blasting log. Before the blast is detonated, the blaster must record:

Date and time of the blastNumber, depth, and placement of chargesLocation of the blast site (identify the location of the blast site as accurately as possible; give the distance to the nearest public dwelling or area)Material blasted (describe the type of rock or other material blasted)Type and size of explosives used in the blastType of detonators used in the blastDelays (describe and show the delay sequence)Electrical devices (describe the circuit and record the results of electrical calculations and measurements; identify the device (machine) used to initiate the E.B. CapsLoading pattern (show the loading pattern, with the burden and spacing between holes, and any nearby structures or roadways; show the delay design and the expected direction of rock movementAll misfires, undetonated explosives, and other hazards (loose rock), as well as the action taken to correct unsafe conditionsThe resistance calculations for each electrical series and circuitThe precautions taken to contain fly materialThe placement of danger area guards

After detonating the blast, the blaster must record the result of the post-blast inspection for misfires and other dangers. Providing the required information is recorded in an organized manner, any format for reporting may be adopted. Some blasters use a diary; others use blast record sheets provided by the employer.

The blasting log must be readily available at the blast site, and must be produced for inspection upon request of an officer of WorkSafeBC. It must be retained by the employer for at least five years following completion of blasting operations at a worksite.

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Blasters must keep a record of preblast loading data and of the examination of the site after the blast.


Blasters and helpers training to become blasters must maintain a personal blasting log containing pre-blast loading details and results of post blast site inspections. See OHS G21.4(4).



Chapter 17: Returning to the Blast Site

After firing a charge, the blaster is responsible for examining the site and clearing dangers caused by the blast. Precautions must be taken before anyone, including the blaster, returns to the blast

site. The blaster and persons authorized by the blaster are the only ones allowed to enter the blast area prior to the all-clear signal.

The blaster conducts a thorough inspection of the site to identify and control any dangers. The all-clear signal is not sounded until the area has been made safe. Any of the following precautions may be necessary following a blast.

Electrical blasting

If a blast has been fired electrically, the firing cables must be disconnected from the blasting machine and the lead wires short-circuited. This is to prevent current passing through the circuit, which may still contain a “live” detonator.

Air contaminants

Air contaminants (dust and fumes) must be reduced to a safe level. Permissible concentrations for dusts and fumes are specified in the Occupational Safety and Health Regulation. As a general rule, no one should return to a blast site if dust or fumes are present.

In surface blasting, dust and fumes rapidly disperse into the atmosphere. In confined areas, they are a more serious problem. Atmospheric tests must be made following a blast, and the space ventilated before workers are permitted to enter. For more information on identifying confined spaces in the workplace and how to prepare and implement a confined space entry program, please see WorkSafeBC's Occupational Health and Safety Regulation, Part 9 Confined Spaces.

Examining the site

The blaster must carefully examine the site for un-detonated explosive materials and other dangers. Equipment operators and others entering the site should be taught to recognize loose wires and un-detonated explosive materials. They must understand a misfire may be handled only by, or under the direction of, a blaster.

The blaster must not leave the blasting site until attending to any un-detonated explosive materials or other dangers caused by the blast.

The all-clear signal is not sounded until the area has been made safe.


In underground workings, it is common practice to blast at the end of a shift in order to allow dust and fumes to clear before the next shift commences work.

Dangers

All dangers must be identified and controlled before other work is resumed in the area. The location of a misfire should be identified by a wooden plug, coloured flag, spray paint, or other effective means.

Control measures can include:Roping off the area surrounding the dangerKeeping metal tools and equipment away from misfiresBracing or supporting loose material that may fall or move

Loose material

Any unstable material that could cause injury or property damage is commonly referred to as “loose material” or “loose.” Examples include:

Broken tree limbsOverhanging rocksUnstable boulders

Approximately 30 percent of blasting-related fatalities in British Columbia has been caused by loose material following a blast. Additionally, many serious injuries and property damage have resulted.

Loose material on a slope or face must be scaled, trimmed, or otherwise stabilized. It is safer and more effective to remove loose material using machinery, such as front end loaders or hydraulic excavators, thus minimizing risk of injury to workers.

Hand scaling is done using a metal scaling bar. The nature of the material can be determined from striking the surface with the end of the bar. A sharp (hard) sound indicates solid rock. A hollow (thud) sound indicates unstable material.

See Parts 20.96 - 20.101 for regulations on scaling.

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Smoke from the muck pile may indicate burning explosive materials that could explode at any moment.


When hand scaling: Wear a safety belt or harness attached to a securely anchored lifelineWear protective footwear and hard hatUse a scaling bar in good condition and of suitable lengthBegin scaling from a safe location, from the top downStand on a solid surface and maintain balanceWatch for holes containing explosive materialsDo not scale above any misfire hole or un-detonated explosive materialsDo not scale where anyone may be endangered by falling rock

After the area is inspected by the blaster and deemed clear of explosive hazards, sound a five-second all-clear signal.

Clean up

Boxes, cartons, and liners that have contained explosive materials must be collected and destroyed in a safe manner. They must be handled with care to prevent undue impact or exposure to excessive heat. Check that detonators, explosives, or other dangerous substances are separated from other waste material and destroyed in the manner discussed in Chapter 5.

Explosives packaging may not be re-used for any other purpose. Before disposal, it should be thoroughly inspected for any leftover explosive or residue. Preferably, boxes and bags should be burned. Where this is not allowed, they may be placed in landfill, using the following procedures:

Packaging must be rendered unusable by flattening boxes or slitting bags.The material should be bundled so that no reference to explosives (e.g., name, TDG diamond) is visible.

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Before leaving the blast site, take a few minutes to clean up empty powder boxes, expendable blasting wire, burned safety fuse, used tubing, and other waste materials.


Chapter 18: Misfires

Misfire” means any part of an explosive charge that, after initiation, fails to completely detonate. Any misfire is potentially dangerous. When preparing the blast, every

precaution should be taken to minimize the risk of a misfire.

Regardless of precautions taken, misfires can still occur. Therefore, a blaster is expected to know the causes of misfires, recognize their indicators, and understand safe procedures for handling them.

Types of misfires

There are two categories of misfires:HangfiresGeneral misfires

A hangfire is an unplanned delay in the detonation of an explosive charge, which can occur in any part of the system that is contaminated, damaged, or otherwise defective.

General misfires include any blast or hole that does not fire or any blast that does not detonate as expected.

Causes of misfires

Common causes of misfires include:Explosive:

DeterioratedCold or frozenImproperly mixed (AN/FO)

Detonator:DeterioratedDamaged

Safety fuse:Powder core is moist or contaminatedFuse is cut, kinked, or otherwise damagedFuse is not properly ignitedLow quality of fuse or assembly

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A hangfire CAN DETONATE ON ITS OWN at any time!

All misfires are dangerous — treat them with extreme caution!

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Charge:Detonator has become detached from chargeCharge units are separated by gravel or other materialToo much space between individual charge units

Stemming:Inadequate or no stemming

Initiation system:Incorrect use of initiation systemDamage to initiation systemImproper use of delay detonators or detonating connectors

Electrical initiation:Blasting wire damaged or inadequateBlasting wire shorted out, improperly connected, or imperfectly joinedCurrent leakage in blasting circuitBlasting machine damaged or defectiveBlasting machine improperly usedApplication of insufficient or excessive electrical current

Other reasons:Explosive materials exposed to high temperaturesInadequate priming of the chargeFailure to examine the blasting circuit or tie-inCharge or part of charge “dead pressed” by the detonation of an adjacent chargeCharge or part of charge “cut off” due to excessive ground movement (such as, fracture, fault, joint)

Indicators of misfires

The indicators of a misfire depend on the explosive and the initiation system. Common indicators include:Noise:

Upon initiation, is there any noise?Is the "noise" as expected?

Explosive materials:Are explosives, detonating cords, or detonators scattered about the blast site (e.g., cartridges, detonating cord, shock tubing)?Are explosive materials protruding from a hole?

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The indicators of a misfire depend on the explosive and the initiation system.


Muck pile:Is the muck pile the size, location, and shape expected?Are there “oversize” boulders in the muck pile?Is smoke rising from the muck pile? (may indicate burning explosives)

Other indicators:Did the explosive charge have the expected effect?Is there an excessive amount of fly material?Does the rock face have humps or cavities?Were there orange/yellow tinted fumes? (could indicate nitrous oxides, a product of improper detonation)

These indicators should cause a blaster to suspect a misfire.

Minimum waiting times

When a misfire is known or suspected, no person is allowed to return to the blast site until the expiration of an appropriate minimum waiting period.

Misfired charge

The following waiting times are appropriate for misfired charges:10 minutes after firing a blast using an electric detonator, or30 minutes from the expected detonation of a safety fuse charge or the waiting time as recommended by the manufacturer.

With the exception of safety fuse, the minimum waiting time for all initiation systems is at least 10 minutes after firing the blast.

Safety fuse has greater delay potential. It may burn more slowly for a number of reasons, including moist powder, damaged fuse, and high altitude.

Burning charge

If a charge is known or suspected to be burning, the waiting period is at least 60 minutes. Smoke originating from a blast hole may indicate burning explosive materials.

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IntheRegulation

Part 21.36 General

Explosive materials must be stored, transported, handled and used in the manner recommended by the manufacturer.

The Occupational Health and Safety Regulation requires that the blaster follow manufacturers’ recommendations. If the manufacturer recommends longer waiting times, the blaster is obligated to follow that recommendation.


Burning explosive materials are highly sensitive and can detonate on their own at any moment. Keep everyone away from a burning charge for the minimum waiting time (one hour after last visible smoke), and longer if necessary.

Make no attempt to extinguish burning explosive materials.

Personnel

Keep the number of persons in the blasting area to a minimum; only the blaster and those required to assist are allowed in the blasting area. Helpers should be experienced workers selected from the blasting crew.

Until all dangers are eliminated or controlled, treat the blasting area as a “danger area” and post guards to prevent others from entering.

Removal by hand

The blaster must have as much broken material as possible removed by hand before metallic tools or equipment are used. Sparks from metal equipment and tools can cause accidental detonation.

Metallic equipment

Do not use metallic equipment to remove broken material unless:A blaster directs the use of the equipmentThe illumination of the area is adequatePrecautions are taken to prevent injury in the event of accidental detonation

When using an excavating machine or a bulldozer, all persons — except for the blaster and the operator — should be removed from the area. Adequate safeguards must be provided to protect the blaster and the operator in the event of an accidental detonation.

Specific misfire procedures should be developed for the explosive materials being used. Advice can be obtained from the manufacturer or manufacturer’s representative.

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IntheRegulation

Part 21.73 Misfires

(1) When a blast initiated by electrical methods cannot be verified to have completely detonated, or is suspected to have misfired, the blaster must disconnect the firing lines from the blasting machine, and wait at least 10 minutes before permitting anyone to enter the danger area. (2) When a blast initiated by a safety fuse cannot be verified to have completely detonated, or is suspected to have misfired, the blaster must wait at least 30 minutes after the estimated time of detonation before permitting anyone to enter the danger area.


Identification, destruction, and removal

When a misfired charge is located, blasters must adhere to the Occupational Health and Safety Regulation.

IdentificationA hole containing a misfired charge, commonly known as a “mishole,” must be identified by a wooden marker or by:

Spray painting the collar of the holeStuffing a coloured rag in the open end of the holePlacing a plastic cone in or near the collar of the hole, orTying coloured “survey” flagging to a stake near the collar of the hole

DetonationOnce a misfired charge has been located and identified, it must be destroyed before other work commences. Misfired charges are usually destroyed by detonation, using a fresh primer. Misfires should be treated like any other blast: warning signals should be sounded and the danger area guarded. Blasters should never attempt to relight a length of safety fuse; if shortened, it could cause premature detonation, or if damaged, could result in a hangfire.

RemovalNO ONE is permitted to remove, relight, or disturb a fuse, detonator, part of a charge, or a misfired charge, except under the following circumstances:

A blasting agent may be blown out with air, water, or a combination of both. Use ONLY water in a hole containing an electric detonator. Use a fresh primer to blast the old primer.It may be necessary to remove stemming material from a loaded hole in order to re-prime the charge. Stemming may be removed by:

A non-sparking (wooden) spoon or similar devicePressurized water, or air and water, but not air alone

Stemming material must be removed carefully. Do not disturb or remove any part of the explosive charge. Once the misfired charge is uncovered, place a fresh charge near it, re-stem if necessary, and fire the shot in the usual manner.

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IntheRegulation

Part 21.77 Marking and Detonating (1) Each misfired charge must be clearly marked and the area cordoned off.

(2) No attempt must be made to remove an unexploded charge and no other work may take place within the blasting area, until the misfired charge has been successfully detonated by rewiring or repriming with a fresh primer.


Drilling to re-fire

Drilling an additional hole to re-fire is permitted, but only if:The angle of the misfired hole is accurately determinedThe blaster who placed the misfired charge directs the angle and depth of the hole being drilledThe hole being drilled is at least 600 mm (2 ft) from any part of the misfired charge

If any of the above requirements cannot be met, the misfired hole must be treated as a loaded hole and drilled in accordance with the procedures in Chapter 12.

The purpose of the additional hole and charge is to remove the overburden and expose the misfired charge so that it can be blasted with a fresh primer. Since the additional charge must be at least 60 mm (2 ft) from the misfired charge, it is unlikely propagation will occur.

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Chapter 19: Non-electric Initiation Systems

Safety fuse

Safety fuse has a special black powder core in a spirally wrapped cover of textiles and waterproof materials. The cover protects against contamination and abrasive damage, and allows the fuse to convey flame to the detonator at a uniform speed.

Safety Fuse

The burning speed of safety fuse is 131 seconds per metre (40 seconds per ft) at sea level, with an allowable variation of plus or minus 10 percent.

The burning speed may be affected by:Excessive tamping, which compresses the powder granules and causes the fuse to burn fasterHigh altitude, which exerts less external pressure on the powder granules and causes the fuse to burn slowerMoisture, which when absorbed by the powder causes the fuse to burn slowerChemicals, oil, and solvents, which can destroy the outer cover and contaminate the powder, causing the fuse to burn slower (hangfire) or fail to burn (misfire)Kinks and bends, which can cause the fuse to burn faster, but are more likely to make it burn slower (hangfire) or fail to burn (misfire)

If the specified burning speed is to be maintained, it must be stored in a cool, dry, well-ventilated magazine. Rotate stock by using old fuse first.

Safety fuse assembly

A safety fuse assembly is comprised of a length of safety fuse with a detonator attached to one end, and usually has an igniter cord connector on the other end.

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CentreThreads

FusePowder

PlasticSleeve

CottonYarn

Jute&SyntheticYarn

AsphaltCoating FinishingWax

IntheRegulation

Part 21.57 Lighting safety fuse (2) When multiple safety fuses are to be lit, a suitable safety fuse lighting device must be used to ensure that a minimum 90 cm (3 ft) fuse length safety factor is maintained.


Fuse length

The shortest manufactured safety fuse assembly is 1 m (3.3 ft) long. In some applications, it may be necessary to “trim” a fuse assembly by removing the igniter cord connector or a section of fuse.

If several fuses are to be ignited by means other than igniter cord (for example using a hot wire lighter), minimum fuse length must be increased accordingly. Allow sufficient time to light all the fuses and walk — not run — to a safe place, with at least 30 seconds to spare.

Fuse handling

Handle safety fuse carefully. Avoid bending, pinching, or twisting it.

Detonator

The detonator (blasting cap) is an initiating device capable of detonating most explosives. It has an aluminum shell approximately 6 mm (1/4 in) in diameter and 48 mm (1 7/8 in) long, with a composite charge pressed into the base end.

The composite charge comprises a priming charge and a high explosive. The priming charge is heat/flame sensitive and composed of lead azide and lead styphnate. The high explosive is PETN (pentaerythritol tetranitrate).

The flame spit from the safety fuse ignites the priming charge, which in turn detonates the PETN compressed into the base of the shell.

Static shunt

All detonators used in manufactured safety fuse assemblies contain a “static shunt.” A metal staple is embedded in the detonator, touching the shell and penetrating through the fuse to the powder core. The staple drains off static electricity preventing premature detonation.

The static shunt does not guarantee total immunity from static and other electrical hazards. Therefore, a fuse assembly should not be used if excessive amounts of static or other extraneous electricity is known or suspected to be present.

Damaged or deteriorated fuse must not be used; it can result in a hangfire or a misfire.


Igniter cord connector

The igniter cord connector is a metal tube containing a pressed ignition composition. This connector keeps the fuse end clean and dry, and readily ignites under most conditions.

The copper alloy metal tubing is similar to a detonator shell, except for a slot in the base end designed to hold the igniter cord in contact with the ignition composition. Once the igniter cord is inserted, the flap at the base of the connector is pressed down to secure the connection.

When a lighting device other than igniter cord is used, the flap may be broken off to expose the ignition composition. This composition has excellent resistance to moisture. It can be exposed to water (less than 48 hours) and remain easy to ignite. However, the cooling effect of water may reduce its ignition capability.

Unless damaged or deteriorated (or unless the assembly is to be ignited by a pull wire lighter), an igniter cord connector should not be detached from an assembly.

Igniting the safety fuse assembly

Igniting a safety fuse assembly is a critical operation. Difficulties in lighting one assembly while others are burning have resulted in accidents and serious injury. Therefore, the safety fuse and the lighting device must be in good condition.

Safety fuse is easy to ignite, providing the lighting device has an intense (hot) flame and the fuse end is clean and dry. An igniter cord connector makes lighting the fuse much easier.

If an igniter cord connector or a fuse end is moist or contaminated, approximately 25 mm (1 in) must be cut from the end before an attempt is made to ignite it. This is known as “trimming” the fuse. In no case should a fuse assembly be trimmed to less than 90 cm (3 ft).

Acceptable lighting devices

A safety fuse assembly must only be ignited using a device acceptable to WorkSafeBC. Smoldering or open flame devices such as cigarettes, cigarette lighters, and propane torches are not acceptable for lighting a fuse assembly. Such devices are unreliable and could endanger persons in

Do not apply excessive force or twist the fuse. Serious damage or premature ignition could result.


the blasting area. Furthermore, smoldering materials and open flames are prohibited in a blasting area.

Four devices are acceptable for lighting fuse assemblies:1. Safety match: Safety matches are permitted if not more than one fuse assembly is

to be ignited in one operation. Safety matches produce a flame of medium intensity and short duration.

2. Fusee match: Fusee matches have an enlarged tip and are more reliable than a safety

match. A fusee match can be used to ignite 2 or 3 assemblies if they are clean, dry, and in close proximity. However, other devices are more reliable.

When lighting safety fuse or an igniter cord connector with a safety or fusee match, keep hands and fingers away from the fuse end. Upon ignition, it produces a jet of flame (“ignition spit”) capable of causing a painful burn.

3. Pull wire lighter: A pull wire lighter is a flame-producing device used with a single

fuse assembly. It is effective where high winds could hamper other methods of ignition.

To prepare the assembly, remove the igniter cord connector from the end of the fuse, making a square cut. Make sure the inside of the pull wire lighter and the exposed end of the fuse are clean and dry.

To attach the pull wire lighter, gently insert the fuse about 50 mm (2 in) into the open end of the tube. Internal teeth will hold it in place. Do not apply excessive force or twist the fuse. Serious damage or premature ignition could result.

Make sure the inside of the pull wire lighter and the exposed end of the fuse are clean and dry.

Hot Wire Lighter and Box

Pull Wire Lighter and Box


To activate, hold the tube securely and firmly pull the handle. This will produce an internal flame jet and ignite the fuse.

4. Hot Wire Lighter: A hot wire lighter is a stiff wire coated with an incendiary composition

that burns with great intensity without flaming. It resembles a fireworks sparkler, and can be ignited with a safety match. When lit, it is held against the igniter cord connector or the exposed end of the fuse assembly.

Hot wire lighters are available in three lengths with different burning times and lighting capabilities.

Table 2: Hot Wire Lighters

Hot Wire Lighter Length Approximate Burning Time

Not Recommended for Igniting More than

178 mm 7 in 60 seconds 10 assemblies



NOTES:1. Recommended quantities refer to fuse assemblies with clean, dry

ends, located in close proximity to each other.2. Since moisture and other contaminants may affect the burning time,

a hot wire lighter must not be used as a timing device.

Determining ignition

A blaster must be able to determine that a fuse is actually burning. Three simple checks can be made.

Did an “ignition spit” occur? (This is the flame jet that shoots out the end of a fuse when it is ignited). An igniter cord connector will also “spit.”Does a steady stream of smoke rise from the fuse? (Additionally, a hissing sound may be heard.)Is the fuse hot? As a last resort, gently touch the fuse. It will be very hot if the powder core is actually burning. Also, at the point where the fuse is burning internally, the fuse will become very flexible and limp.

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A blaster must be able to determine that a fuse is actually burning.


As the fuse burns, the outer covering darkens. Remember the powder core in the fuse burns ahead of discoloration on the outer covering, or heat.

As soon as a blaster knows or suspects that a fuse is burning, everyone must leave the area and go to a safe place before the first charge detonates.

Hazards and precautions

The principal causes of premature detonation are abuse and exposure to heat. Impact or shock can compress the explosive charge in the blasting cap to the extent that it will detonate. Temperatures in excess of 66° C (150° F) can ignite the sensitive detonator.

Accidental detonation may also result from improper ignition techniques and mishandling.

Do not mishandle detonators, tamper with them, or expose them to heat sources. The human body can generate temperatures that will affect the sensitive compositions in a detonator. Therefore, do not carry them in clothing, and avoid holding one in the closed palm of the hand.

Care must be taken when handling fuse-lighting devices. Mishandling could impair their efficiency or cause them to ignite prematurely. When lighting fuses, keep the device away from detonators or heat sensitive explosives.

Several blasters who did not realize the fuse was burning, or who delayed too long after lighting the first fuse, have been seriously injured or killed. When more than one fuse assembly is ignited, everyone must vacate the blast site well in advance (at least two minutes) of the expected detonation of the first charge.

Returning to the blast site too soon has resulted in numerous accidents. Should a misfire be known or suspected, wait the prescribed amount of time (see Chapter 18).

To guard against premature detonation, detonators should be kept in a crush-resistant container until ready for use.

Do not keep or store igniter cord with explosives or detonators.

Ignition Spit from End of Fuse


Chapter 20: Detonating Systems

ExplosiveCore

InnerBraid

PlasticSleeve

TextileCountering

WaxFinish

Detonating cord system

Detonating cord is a flexible linear explosive used to initiate other explosives directly, or with a booster/primer. In applications such as forest fire control, welding, perimeter or pre-shear blasting, it is used as the main explosive charge.

Detonating cord

Detonating cord has a core of high velocity explosive contained in a plastic sheath, wrapped in various combinations of textiles, plastic, and wax coverings.

Sectional View of Typical Detonating Cord

The core explosive is usually PETN (pentaerythritol tetranitrate). When initiated by a “high strength” detonator, these cords explode with a velocity of over 6,705 m (22,000 ft) per second.

Detonating cord has several layers of covering material. Typically, an inner braid, a plastic sleeve, a textile covering, and a wax finish protect the core from abrasion, moisture, and damaging substances. The flexibility allows most cords to be readily tied together and used in a wide variety of applications.

Detonating cord has good storage properties and is relatively safe to handle. Under proper conditions, it is not affected by temperature extremes and has low sensitivity to premature or accidental initiation from:

Friction Heat Static electricityImpact

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It is not immune from contact with machinery, rock falls, or lightning strikes. Since all explosives can be detonated, detonating cord must be treated with respect.

Depending on its usage, or location in a blasting circuit, detonating cord is often referred to as:

Downline — the length of cord located in the blast holePigtail — the exposed portion of downline at the collar of the holeTrunkline — the length of cord to which the downlines (pigtails) connectBranchline — the trunkline serving each row of holes; branchlines are attached to a main trunklineCross-tie — a connection between branchlines that provide an alternate path of detonation

Detonating Cord Circuit

There are several types of detonating cord, each with different strength core explosive and/or quality of outer covering. Explosive strength is usually expressed in terms of grams (grains) of PETN per linear metre (foot) of cord or gm/m (gr/ft). Tensile strength is based on the durability of the outer covering.

The multiple plastic and textile covering offers exceptional protection from contact with loading hoses, fuel oil, and hot solutions used in bulk slurry/watergel formulations. The higher initiating energy ensures optimum initiation of cast primer compositions, while flexibility and knot-tying properties are maintained throughout extreme ranges of weather and temperatures.

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Branchlines

CrossTie

Trunkline

Pigtail


Storage and handling

Detonating cords are kept or stored with explosives. Detonating connectors that contain sensitive “primary” explosives must be kept or stored with detonators, and not with detonating cord or other explosive materials.

Protect detonating cords and connectors from damage, heat, impact, and other abuse. Damaged cord could result in a misfire. Damage to a detonating connector could result in accidental detonation or a misfire.

Each reel of detonating cord must be treated with respect. It should not be thrown or allowed to come in contact with tools, rocks, or other sharp objects.

Detonating cord can be damaged by:Scraping action on metal and rock surfacesContact with bulk loading hosesBeing driven over by vehiclesShovels used to place stemmingCoarse or jagged stemming materialFrozen chunks of stemming

Cut detonating cord with a knife or cord cutter. Ensure the cutting edge is sharp and clean. A cord cutter should have a single cutting blade acting against a brass plate or non-metallic surface.

After cutting detonating cord, the cord ends should be sealed with tape or a plastic sleeve. Not only will this keep the explosive clean and dry, but the PETN (white powder) will not spill from the cord.

All cutting tools should be cleaned to remove any PETN on the metal surfaces or moving parts. PETN with grit or metal may result in accidental detonation.

Loading procedures

Detonating cord is used in many operations as a means of initiating explosives in a borehole. The following procedures should be adhered to when loading a hole with detonating cord:

Attach the detonating cord to the first cartridge or primer loaded into the hole.Use a stand, or hold the reel with a rod through the axial hole, to allow

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Detonating cords and detonating connectors contain powerful explosives. They must be properly stored and handled with respect.


the detonating cord to run smoothly from the reel.Lower — do not drop — the primer to the bottom of the hole.Ensure the primer is at the desired position in the hole, preferably the bottom (toe).Cut the detonating cord from the supply reel before, or as soon as possible after, the charge is placed; keep the reel a safe distance from the loaded hole.Allow 900 mm (3 ft) or more of extra detonating cord to compensate for the charge slumping in the hole, and for making later surface connections.Hold the detonating cord taut to one side of the hole so it is not damaged by, and does not interfere with, loading and stemming the hole.Secure the exposed end of the cord to prevent it being kicked or pulled in by the explosives slumping in the hole; it may be fastened to a rock or a wooden dowel. Be sure to leave enough slack to allow for some slumping.

Layout patterns

Detonating cord is often used to initiate a blast pattern containing one or more rows of loaded holes. The following diagrams illustrate typical layouts of trunkline for single and multiple row patterns.

Single row pattern

In a single row pattern, the downline (pigtails) in each row of loaded holes are connected to a single trunkline.

Single Row Pattern

In the preceding diagram, the “O” represents a loaded hole, and the solid line a length of detonating cord. The connections are kept at right angles to, or in the general direction of, the path of detonation.

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PointofInitiation

DetonatingCordCartridgePrimer

CloveHitch,DoubleHalfHitchorDouble

WrapHalfHitch


Multiple row patterns

In multiple row patterns, downlines in each row of holes are connected to a branchline. The branchlines are then attached to the trunkline, and one or more cross-ties are inserted to provide at least two paths of initiation.

When cross-ties are used, all connections must be at right angles to prevent a cut-off from the alternate path of initiation. Since a cross-tie provides a second path, the detonation wave may originate from opposite directions.

In the following diagram, three branchlines are connected to a main trunkline. There is a cross-tie between the branchlines to provide a second path of detonation. In multiple row patterns, a cross-tie should be used to connect the ends of the branchlines.

Multiple Row Patterns

MS Connectors

MS Connectors can be used with detonating cord to provide millisecond delay intervals along a line of propagation. They consist of a length of shock tubing with an identical delay detonator on each end. Each detonator is contained inside a connector block to which the ends of the trunkline are attached. Each delay detonator fires in one direction only, although the assembly itself is bi-directional. It is more reliable than a single element connector, and delay times are more precise.

In operation, the detonation wave from the incoming cord bypasses and renders redundant the delay device in the first connector block, simultaneously initiating the shock tube. An explosive signal is transmitted by the shock tube to the delay device in the second connector block. The

PointofInitiation

PathofDetonation

MS Connectors can be used with detonating cord to provide millisecond delay intervals along a line of propagation.

In the diagram on the right, there are no delays to provide “relief” between rows of holes. Delays are obtained between holes, or rows of holes, using detonating connectors.


signal is arrested for a number of milliseconds, then the receptor detonator fires to initiate the outgoing detonating cord.

MS Connectors are factory assembled, sealed units available in a range of (millisecond) delays, colour coded accordingly. They are suitable for use with detonating cords.

MS Connectors

The following diagram illustrates a typical blast pattern using detonating connectors to achieve the desired delay between holes with approximately the same burden.

Typical Blast Pattern Using Detonating Connectors

Note: “x” represents a detonating connector. The use of delays in the circuit allow the front (and centre) portions to detonate first and provide “relief” for the holes to follow.

For advice on detonating cord patterns, contact the manufacturer or manufacturer’s representative.

PointofInitiation

PathofDetonation


Connecting charges

Connecting or joining charges together includes hooking up detonating cord and wiring up electrical detonators. Charges should not be interconnected until the last possible moment. However, interconnecting charges within the hole at the time of loading, as in deck loading, is permitted.

Except for interconnecting charges in the same hole, an explosive charge must not be connected to another charge, nor attached to a trunkline until immediately before the intended time of detonation.

Charges should be interconnected in an orderly, systematic fashion, beginning at the end of the circuit and working toward the point of initiation. Connections should be neat and the surrounding area kept tidy.

Hooking-up procedure

Do not interconnect detonating cord:Until all holes are loadedImmediately before the intended time of detonation

An accidental detonation will affect all interconnected charges; therefore, avoid hooking up until the last possible momentBegin connections from the furthest part of the circuit and work toward the point of initiationKeep connections tight and secure; avoid in-hole connections; if this is not possible, make a tight knot and secure the ends with electrician’s tapeRemove excess cord from the pigtails after tying-in — this prevents cutting off the trunkline; destroy cut-off ends in a safe manner (place them in the last hole of a blast pattern)Keep connections 90° or less to the path of detonation — acute angles can cause a cut-off, or the detonation wave will bypass a detonating connector; this is more likely in underwater blasting operationsIf a blasting pattern contains a cross-tie, keep all connections at right anglesEnsure there are no loops, sharp angles, or kinks that direct the cord back toward the oncoming detonation pathEnsure the circuit has no excessive slack and the cord is undamagedA multiple row blast using trunkline must have cross-ties between the rows:

To provide at least two paths of initiationAt intervals not exceeding 30 m (98 ft)

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Charges should not be interconnected until the last possible moment.

Ensure the inner cores of both detonating cords are dry; a wet core may fail to propagate


Cross-ties protect against cut-offs from fly material and ground movement; they should be spaced at closer intervals if the burden and spacing are small, or the ground brokenKeep the blast site clean so the detonating cord layout is readily visibleDetonators must not be connected to the detonating cord until the circuit is checked and everything is ready for the blast

Connections

Detonating cords are spliced or connected together using knots, plastic connectors, or tape. A reel of detonating cord may contain a factory splice (an overlap connection secured by a string tie). This splice must not be used in a blasting circuit. When a splice is encountered, the string should be removed and a connection made using a standard knot.

Knots

Knotted connections are popular. The flexibility and wax surface of most detonating cords make knot tying easy and reliable under most conditions and temperatures.

Common knots include:The “square” or “reef” knot — recommended for joining lengths of detonating cord; ends should be secured (with electrician’s tape) or trimmed (not too short!) so they do not lie across trunklines or downlines and cause cut-offsThe “double half-hitch” — a popular connection between downlines and trunklines; pull the knot tight so the lines are in positive contactThe “clove-hitch” and “double wrap half-hitch” — used for connecting trunklines to downlines, or to connect cross-ties and safety lines in a required configuration

Clove-hitch Double Half-hitch Double Wrap Half-hitch Square or Reef Knot

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Plastic connector

A plastic connector may be used to connect downlines to trunklines. It is useful under extreme conditions or long exposure prior to blasting. It does not contain explosive and should not be confused with a plastic detonating connector.

Plastic Connector

Taping

Two lengths of detonating cord may be connected by overlapping the ends at least 100 mm (4 in), and taping them together with electrician’s tape.

Taping Overlapped Ends Together

Tape connections are sometimes used to connect “pigtail” detonating connectors to a trunkline. This is not recommended, however, as the connection has poor tensile strength, particularly in cold temperatures. A knot secured with tape is preferable.

Initiation procedures

Detonating cord is designed to be initiated by a “high strength” detonator. Also, one type of detonating cord may be initiated by another type of detonating cord (except for low coreloads 18 gr/ft). Other explosives are considered unreliable for initiating detonating cord.

At least one manufacturer recommends, and many blasters use, two (2) detonators at each initiation point. This is known as “double priming.” The second detonator is good insurance and should be used whenever the blast is critical and the charge not easily recovered.

Detonating cord is designed to be initiated by a “high strength” detonator.


Detonators to initiate detonating cord should be attached as follows:Bend approximately 200 mm (8 in) of the initiating end of the detonating cord into a loop; place the detonator in the loop with the base end pointing in the direction the shock wave will travel.With the detonator(s) held tightly in position, secure them in place with electrician’s tape; keep the base end of each detonator in contact with the cord.Leave approximately 6 mm (1/4 in) of the base end exposed, to check for misfires without disturbing the connection.If electric detonator(s) are used, connect them in a single series circuit and thoroughly tape all connections.

Safety procedures

When using detonating cord or detonating connectors:Select the appropriate detonating cord for the job; if in doubt, consult the manufacturer or supplierKeep and store:

Detonating cord with explosivesDetonating connectors with detonators

Keep cord supply reels in the shipping case before and after useUse a hand-held rod or a stand when removing cord from a reelCut the cord from the reel before, or as soon as possible after, loading a hole; move the reel to a safe location — an accidental detonation within a hole could detonate the reel on the surfaceAfter loading and cutting the downline from the reel, secure the pigtail to a wooden dowel or other anchor if there is any possibility of the pigtail slipping into the holeAvoid abrasion to the cord from hole collars, casino pipes, or other sharp edgesAvoid in-hole connectionsUse proper knots, and ensure they are tight and secureEnsure connections are at right angles; if a cross-tie is used, keep all connections at right anglesTo ensure initiation, use two detonators at each ignition pointAttach detonators with the base end contacting the cord pointed in the intended direction of propagation (toward the main part of the charge)Collect all scrap pieces of cord and destroy by connecting them to the end or back row of the blasting circuit

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Unused explosives, detonators, and detonating connectors must be returned to the storage magazine or destroyed in a safe manner.


Shocktube

Shocktube is a hollow plastic tube lined with finely powdered explosive composition, which when properly initiated propagates a shock wave at a velocity of approximately 2,000 m (6560 ft) per second, or 2 m (6.6 ft per ms). This energy reacts through the primary charge (and any delay element) in the detonator causing the PETN to explode.

Lateral energy is contained within the tube, which remains intact and has no effect on an explosive in contact with it. This feature allows the shocktube assembly to be used with any explosive, regardless of its sensitivity.

The plastic shock tubing stiffens at lower temperatures but will not shatter or crack unless it has surface nicks or abrasions. Under conditions of careful handling and loading, shocktube assemblies have been used in temperatures as low as -40° C (-40° F).

Shocktube Initiation Systems

Shocktube initiation systems introduce a variety of timing options. (For more information on MS Connectors, see page 82).

Shocktube assembly

The shocktube assembly is a sealed unit, available in a range of tubing lengths. The shock tubing is securely crimped to the detonator, and the other end is closed with a heat seal.

No person should hold shocktube tubing or be in close proximity when it is initiated; a flaw in the manufacture or damage to the tubing could cause serious injury.

Follow the manufacturer’s instructions concerning the correct trunkline and connection configuration for each type of assembly. Do not use lower strength detonating cord; it may fail to initiate the tubing.

Never remove the heat seal or cut the tubing to shorten an assembly.

Shocktube ReinforcingTextiles

OuterPlasticJacket


Sectional View of a Shocktube Assembly

Shocktube detonator

The detonator has an aluminum shell approximately 7.5 mm (1/3 in) diameter, and between 58 and 84 mm (2 1/8 and 3 1/4 in) long, depending on the delay period. A composite charge of heat sensitive (lead azide) and high explosive (PETN) is pressed into the base end. The shell may also contain a millisecond (ms) delay element.

The shock wave from the shocktube tubing enters the shell and reacts through the delay element, igniting the primary charge, which in turn detonates the base charge of PETN.

Shocktube detonators are either short or long delay types, each having different periods and average delay intervals.

Storage and handling

Shocktube must be kept sealed, dry, and uncontaminated. If cut, nicked, or otherwise damaged, it may not function properly. With the exception of the heat seal, it has good resistance to moisture and fuel oil. The tubing and detonator are impervious to moisture, but fuel oil can penetrate the plastic tubing. Prolonged exposure to AN/FO mixtures can result in failure to initiate or propagate. It must not be exposed to AN/FO mixtures or other oil-containing explosives in a loaded hole for more than a few days.

Shocktube assemblies must be properly stored and treated with care. Do not throw them or allow them to contact tools, rocks, or other sharp/jagged objects.

Since the detonator contains sensitive explosive, all shocktube assemblies must be stored with detonators, not with detonating cord or other explosive materials. Detonating cord must be stored with explosives, separate from assemblies or other detonating devices.

Shocktube

RubberClosurePlug


StaticProtection

DelayElement BaseCharge

InitiatingChargeHeatSeal Connector

Shocktube must be kept sealed, dry, and uncontaminated. If cut, nicked, or otherwise damaged, it may not function properly.


Assemblies must be protected from high temperatures and damaging substances. Temperatures in excess of 75° C (167° F) can cause the tubing to soften.

Damage to shocktube can occur as a result of the following:

Scraping action on metal and rock surfacesContact with bulk loading hosesBeing driven over by vehiclesShovels used to place stemmingCoarse or jagged stemming materialFrozen chunks of stemming material

Never cut shocktube unless preparing a leading line connection. Moisture can enter the explosive lining and render it insensitive. Also, a blow-out may occur through the open end and prevent the detonation wave from reaching the detonator. Never tug on shocktube. If it breaks, there is a slight chance that it may initiate ("snap, slap and shoot") and fire the borehole.

Priming and loading

The shocktube assembly contains a “high strength” detonator capable of initiating many types of explosives. To reliably initiate insensitive explosives, a high-strength booster may be required.

Under normal conditions, plain tubing may be appropriate. However, under adverse conditions, reinforced tubing may be required.

When loading a hole with a shocktube assembly:Use sufficient tubing to allow a 900 mm (3 ft) pigtail at the collar of the holeLower — do not drop — the primer into the holeDo not use the shocktube as a lowering line on a heavy primer — the weight of a primer will damage or stretch the tubing and cause a failure; use a special lowering rope with a self-releasing hookEnsure the primer is in the desired position in the hole, preferably the bottom (toe)Hold the shocktube taut to one side of the hole during loading and stemming; this will prevent damage to and displacement of the detonatorEnsure the tubing does not tangle around the bulk loading hose, and that the primer does not “float” up on a slurry/watergel column

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Do not use the shocktube as a lowering line.


When loading is complete, at least 600 mm (2 ft) of shocktube should protrude from the collar of the hole to facilitate later surface connections. If necessary, secure the tubing to prevent it being kicked in or pulled in by the explosives slumping in the hole; leave sufficient slack to allow for some slumping.

Use care in stemming the hole. Avoid frozen chunks and excessively coarse jagged material. Also avoid contacting the tubing with shovels or other tools.

Side View of Typical Loaded Hole

Shocktube patterns

In a blast consisting of many holes, it is desirable to allow the holes closest to the free face to fire first, and the holes at the back of the blast to fire after some delay. By doing this, the holes fired first allow some “relief” of the burden, allowing the back holes to become more efficient.

The back hole will not move without “relief” and will tend to blow upward. The following are generally accepted as points of good design for large blasts:

The delay time between holes in a row should be between 1 and 2 milliseconds per foot of spacingThe delay time between rows should not normally be less than 2 milliseconds per foot of row-to-row burden, and not more than 6 milliseconds per foot of burden

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Shocktube assemblies and trunkline may be used in single or multiple row blast patterns.

ShocktubeAssembly

Detonator


CastBooster

ExplosiveColumn

Connector


Shocktube assemblies and trunkline may be used in single or multiple row blast patterns as illustrated below.

Single row pattern

In a single row pattern, the shocktube (pigtails) in the row of loaded holes are connected to one trunkline.

Diagram 1

In Diagram 1, the “O” represents a loaded hole, and the lines represent shocktube and trunkline. The shocktube protrudes from the holes, and the trunkline connects the assemblies in a circuit.

Keep all connections at right angles to, or in the general direction of, the path of detonation.

Multiple row pattern

In multiple row patterns, the shocktube in each row of holes is connected to a branchline. Branchlines are attached to the trunkline, and one or more cross-ties are inserted to provide at least two detonation paths.

Whenever a cross-tie is used in a circuit, the detonation wave may originate from opposite directions. All connections must be at right angles to prevent a cut-off from the alternate detonation path.

In the following diagram, three branchlines are connected to the trunkline. There are two cross-ties between the branchlines to provide a second detonation path. It is recommended the ends of the branchlines are connected to one cross-tie.

PointofInitiation

DetonatorPrimedCartridge

TypicalQuick-Connect


ShocktubeDownline


Diagram 2

In Diagrams 1 and 2, in-hole delays provided by the shocktube detonators are the only method of delaying the sequence of initiation in the blasting circuit.

Shocktube assemblies may be used in conjunction with a surface delay system provided by detonating connectors.

Hooking up shocktube assemblies

When hooking up shocktube assemblies in a circuit:Follow the manufacturer’s directions for using the connectorDo not interconnect shocktube or detonating cord until:

All holes are loaded and stemmedImmediately before the intended time of detonation

Accidental detonation will initiate all interconnected chargesBegin connections at the back of the circuit and work toward the point of initiationAll connections must be made where the explosive core of both cords is dry; wet connections may fail to propagateKeep connections tight and clean; loose, dirty connections can result in cut-offsUse assemblies with the appropriate length of tubing (spliced tubing will not propagate)Keep the trunkline clear of explosives; it could initiate prematurelyDo not cut (trim) the shocktubeKeep all connections at right angles to, or in the direction of, the path of detonationIf there is more than one path of detonation, such as when a cross-tie is used, keep all connections at right angles to avoid cut-offsEnsure there is no damage to the tubing or trunkline and no excessive slack in the circuit

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PointofInitiationPathofDetonation

Advice or information on the shocktube systems may be obtained from the manufacturer or manufacturer’s representative.


A multiple row circuit using trunkline must have cross-ties between the rows:

To provide no less than 2 paths of initiation, andAt intervals not exceeding 30 m (98 ft)

Cross-ties afford protection against cut-offs from fly material and ground movement; at least one cross-tie should interconnect the ends of the branchlinesKeep the blast site clean and tidy, with the shocktube and trunklines clear and readily visibleTo minimize looping and tubing cut-offs from the trunkline, locate connections within 300 mm (12 in) of the collar of the holeIf dynamite or cap-sensitive slurry/watergel explosives are loaded into the hole, make sure the trunkline is not in proximity to these explosivesAs a final check, examine all circuits to ensure the trunkline is at least 150 mm (6 in) from tubing below the connector. If in contact or close proximity, it could sever or damage the tubing.

Interconnected shocktube delay systems

There are a variety of shocktube assemblies available. Some have single-delays, while others have dual-delays.

Single-delay assembly

This assembly comes with a pre-determined length of shock tubing. There is a heat seal at one end, and the other end has a high-strength detonator contained within a removable “bunch block” (or other plastic fitting capable of holding multiple cords of shocktubes in close contact with the detonator).

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Detonators must not be attached to the shocktube or trunkline until the circuit is checked and everything is ready for the blast.

OutgoingLine

BunchBlock

IncomingLine

ShockTubeDownlines


With such a system, a number of assemblies can be interconnected or “daisy-chained” to achieve a delay blast, as in the following illustration.

"Piggy Back" Layout Using a 100ms "Jumper"

The above layout might represent a ditch or trench cut. With five different delays (100, 125, 150, 175, and 200 ms), an infinite range of delays is attained along the line of cut.

The following pattern illustrates another application of the single-delay assembly.

Example Detonating Cord Layout Using In-Hole Delays and Cord Relays

In the above pattern, shocktube delays of 230 ms are used down each hole. On the surface, a detonating cord layout is used to initiate the downlines. However, detonating cord delays are inserted at 10 places in the circuit. The end effect is that the four (4) rows fire at 50 ms intervals. After 200 ms, all rows except the last row of detonating cord have fired. (Also, in each row the corner holes fire 50 ms after the rest of the row.) Similar initiation systems of this design are marketed under a variety of trade names.

100msJumper

7(175ms)

5(125ms) 6(150ms) 5(225ms) 6(250ms)

8(300ms)7(275ms)

230msDelayinEachLoop 50msCordDelays


Dual-delay shocktube assembly

There are a number of alternatives available if blasters want to use a single assembly to accomplish complex delay patterns. The dual-delay shocktube assembly consists of a high-strength detonator on one end, a pre-determined length of shocktube, and a low-strength delay detonator contained within a quick-connect plastic housing.

Delay assemblies can be used for the downhole portion of the shot as well as on the surface trunklines. In this way, the circuit on the surface layout is made up of relatively noiseless shocktube and much quieter and less violent low-strength caps.

Dual-Delay Shocktube Assembly

In the following example, there are two inventory items. In this case, 17 ms and 350 ms assemblies are used to achieve an infinite number of delays in the blast. By “daisy-chaining” the assemblies, the blast can be expanded to any size. Not only can the delays be timed along a row, but the individual rows can also be delayed.

Initiation procedures

Shocktube and trunkline are designed to be initiated by a “high strength” detonator. Any other explosive is considered unreliable.

ConnectionDevicewithLow-StrengthCap

StandardCap

LeadstoOtherCaps

ShocktubeLength

SurfaceDelays(17ms)

Hole1 Hole2Hole3

Hole4

DownholeHSDetonator(350ms)

DirectionofInitiation

Initiation


Safety procedures

When using the shocktube system of initiation:Select the proper assembly and trunkline for the jobAvoid abrasion to the shocktube from sharp or jagged objectsDo not use damaged tubing, as it will not initiate or propagateDo not cut or attempt to splice tubesIf necessary, secure the tubing to prevent it being kicked in or pulled in by the explosives slumping in the holeDo not interconnect the assemblies until the last possible momentEnsure the trunkline is not damaged or in proximity to a sensitive explosiveMake proper connections (ensure that they are tight and clean, and are at right angles to, or in the general direction of, the detonation path)If there is more than one detonation path (when cross-ties are used), keep all connections at right angles to avoid cut-offsWhere necessary, use two detonators at each initiation pointAttach each detonator with the base end contacting the cord, and pointed in the direction of the desired detonation pathCollect all scrap cord and destroy, by connecting the bunches to the end or back row of the blasting circuitReturn all unused shocktube assemblies, detonating cord, and explosive materials to a safe location

“Bunch” blasting method

The “bunch” blasting method, used primarily in underground operations for horizontal and upholes, involves gathering and connecting a number of shocktubes to the trunkline with several wraps of detonating cord.

The following procedures should be followed when connecting plain shocktube assemblies together in the “bunch” blasting method:

Gather together no more than 20 shocktubes from neighbouring holesForm the tubes into a “bunch” with the tubes parallel to each otherSqueeze the “bunch” of tubes together, and bind them with electrician’s tape in two locations about 200 mm (8 in) apartMidway between the tapes, make three (3) complete tight wraps of appropriate detonating cord, and secure it with one or more clove-hitch type loops

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Do not interconnect the assemblies until the last possible moment.

Do not use damaged tubing, as it will not initiate or propagate.


Bunch Blasting

The following precautions should be kept in mind when using the “bunch” blasting method:

Make sure the shocktubes are long enough to allow them to be bunched together without stretching the tubing.Bunch together no more than 20 shocktubes from holes in proximity to each other.Ensure that the tubes are clean, particularly at the point of connection.Do not remove the connector or cut the tubing.An unlimited number of “bunches” can be initiated with a single trunkline; where more than one “bunch” is employed, use suitable cross-ties between the bunches to provide at least two (2) detonation paths.As a final check, examine the circuits to ensure the trunkline is at least 150 mm (6 in) from the tubing below the point where the triple wrap of cord is attached.

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Bunch together no more than 20 shocktubes from holes in proximity to each other.


Chapter 21: Electric Initiation Systems

Electric initiation systems employ detonators designed to be initiated by electrical current. This section deals with the principles of electrical theory and the components and method of standard

electric blasting. Note: exploding bridgewire, Magnadet systems, and electronic detonators are referenced in Appendix 5.

Principles of electrical theory

Before using electric initiation systems, a blaster must understand basic electrical theory.

Electricity is a form of energy that occurs in two forms, dynamic (current) and static (charge). Dynamic electricity involves the flow of electrons along a conductor; this flow is known as current, which is measured in amperes (amps).

The current will flow more easily along a good conductor (copper wire) than a poor conductor (dry wood); the difficulty encountered by the flow of current is known as resistance, which is measured in ohms.

Current moves because of a difference of potential within the circuit; this is known as electromotive force, which is measured in volts. A volt is the amount of electromotive force necessary to move one ampere of current across one ohm of resistance. The following analogy can be used to demonstrate this relationship.

Water tank analogy

A tank contains water. Water flows from a 25 mm (1 in) diameter pipe at the bottom of the tank. The force of gravity causes the water to flow from the pipe, but the flow rate is restricted by the size of the pipe.

Side View of Tank of Water

Force(pressure)

Resistance

Current


In this analogy, the flow of water represents current, the size (diameter) of the pipe represents resistance, and the gravitational pressure represents electromotive force.

An increase in current means more water flows through the pipe. A larger pipe will allow this to happen because it offers less resistance. Conversely, a smaller pipe offers more resistance. The greater the height of water in the tank, the greater the gravitational pressure, which is the force behind the water.

Just as water flows inside a pipe, electric current flows within the solid portion of a conductor. A conductor is any material capable of carrying this flow.

Electricity travels at the speed of light, 300,000 kilometres (186,000 miles) per second. It therefore passes through an electric blasting circuit in a fraction of a second, and initiation of detonator bridgewires is virtually instantaneous. The current is either alternating (AC) or direct (DC), depending on the power source. Most blasting machines produce direct current.

The composition of a conductor determines its resistance to the flow of electrical current. Copper is a good conductor, offering little resistance; iron offers somewhat more resistance. For a comparison of copper and iron wire, see Table 7: Resistance of Copper Blasting Wire in Appendix 4.

The diameter (thickness) of a conductor also affects its resistance. As diameter is increased, resistance is decreased. Wire thickness is expressed in gauge or AWG (American Wire Gauge). Thicker wire has a low AWG number, and thin wire a high AWG number. Wires used for blasting range from 8 AWG to 22 AWG. Leg wires on electric detonators are usually 20 or 22 gauge and firing cable may be as thick as 8 gauge.

Length also affects conductor resistance. As length is increased, the current has a greater distance to travel, hence greater resistance. Resistance increases with each unit of length. Resistance of wire is usually stated in units of 305 metres (1000 feet). See Table 8: Resistance of Standard Electric Detonators in Appendix 4.

The condition of a conductor can affect its resistance. Contamination, deterioration, or damage will usually increase resistance.

In blasting operations, the most commonly used conductor is copper wire.

Blasters' Handbook- �0� -

Basics of standard electric initiation

All standard electric initiation systems use similar components, rely on electricity for initiation, and can be affected by electrical hazards.

They offer advantages over other methods:They are easy to prepare and interconnectThe circuit can be testedInstantaneous initiation reduces cutoffsDelay elements allow sequential blasting The blast can be initiated from a safe location

They have one disadvantage: unwanted electricity can enter the circuit and damage the detonator, or cause accidental detonation.

All electric detonators have protection from extraneous electricity, some more than others. If electrical hazards are ascertained and appropriate precautions taken, there is little danger in using an electrical initiation system.

Components of electric initiation systems

The components of all electric initiation systems are similar in design and construction. Each consists of a power source, an electric detonator, and blasting wire. A testing instrument is used to verify the continuity of each system.

Power source

A blasting machine is designed to produce an electrical current. A blasting switch is designed to control the flow of current from a power source.

Electric detonator

For more information on electric detonators, please see Chapter 3.

Blasting wire

Blasting wire refers to the conductors that transmit electrical current within a blasting circuit. Blasting wire includes:

Leg wires, usually 22 gauge copper or iron wires that project from an electric detonator; they are coated with tin and an insulating layer of plastic

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During electrical storms, electric detonators must not be used.

Electric detonators are to be initiated ONLY by blasting machines and blasting switches.


Connecting wire, a light (18-22 gauge) single strand or double strand of copper wire, with an insulating layer of plastic, usually red or yellow; it is used to connect individual detonators together, and to connect the circuit to the lead wire or firing cableLead wire, a medium (12-16 gauge) copper wire with an insulating layer of plastic, usually yellow; it may be simplex (a single wire) or duplex (two wires separately insulated in a common plastic covering); it is used to connect a detonator or series of detonators to a firing cable or blasting machineFiring cable, a heavy (8-12 gauge) copper wire, usually insulated duplex wires in a strong outer black or white cover; it may extend from the power source to the blasting area, and is connected to the blasting circuit by means of an expendable wire (14 gauge or heavier)

Bare sections of blasting wire, particularly connections, must be prevented from contacting the ground or conductive material by elevating them, or insulating with electrician’s tape.

Connections between lengths of wire in a circuit must be secure and offer little resistance to the current flow. Sections of wire to be joined must be clean and bare.

Similar gauge wires can be joined with the Loop-Twist or Western Union connection. The Loop-Twist is very effective for light (18-22) gauge wire, and the Western Union is used with heavier (8-14) gauge wire. When joining appreciably different gauge wires, the Straight Wrap connection is most effective.

Loop-Twist Connection

Straight Wrap Connection

Western Union Connection

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Blasting wire must be kept away from power lines and other conductors that may induce current into the circuit.


Testing equipment

Instruments specifically designed and manufactured for testing electric detonators and blasting circuits are acceptable.

Such galvanometers, ohmmeters, multimeters and voltameters will have the word “Blaster’s” or “Blasting” on their label. They have a special power cell and/or internal resistors to limit current output to a maximum of 25 milliamps (0.025 amps), less than one tenth of the minimum current required to initiate a standard electric detonator.

Testing equipment must be maintained in good condition. Avoid exposure to cold temperatures as the power cell will become weak and produce an unreliable reading.

Instrument readings will be inaccurate if the needle does not deflect to zero (“0”) when its terminals are shorted. Either it is damaged, not properly calibrated (adjusted), or the power cell is weak and needs replacing.

All testing instruments are designed to verify the continuity of a blasting circuit. Continuity (meaning there is no break in the circuit) is determined by measuring the resistance.

In addition to continuity, multimeters and voltameters are designed to test for current leakage and stray current. Current leakage occurs when a bare wire contacts the ground or another conductor. Stray current is the presence of extraneous current in the blasting circuit.

The testing capability of common types of test equipment is outlined below.

Table 5: Capability of Testing Equipment

Testequipment Continuity CurrentLeakage StrayCurrent

Blasting Galvanometer Yes No No

Blasting Ohmmeter Yes No No

Blasting Multimeter Yes Yes Yes

Blasting Voltameter Yes Yes* Yes*

* limited testing capability

IntheRegulation

Part 21.63 Testing circuits Each electrical circuit must be tested before firing using an instrument acceptable to the Board, and the measured resistance must be recorded in the blasting log.

Blasters' Handbook - �0� -

Blasting galvanometer and ohmmeter: The galvanometer, a special type of ohmmeter, is designed for testing continuity. It is commonly known as a “galvo” or “tester.”

Other versions are available. Digital galvanometers produce a numeric display of the resistance. Some manufacturers call their instrument a “blasting ohmmeter.” All galvanometers and blasting ohmmeters have a special power cell and/or internal resistors and two bare terminals.

Blasting multimeter and voltameter: These are precision instruments designed to measure ohms, volts, and amperes (stray current). They have a special power cell and/or internal resistors and a switch to select the appropriate scale of measurement.

Both can be used as a galvanometer (to measure resistance and test blasting circuits), as a voltmeter (to measure voltage and stray current), and to measure the voltage output from a blasting machine or powerline.

Most are capable of measuring alternating current (AC) and direct current (DC).

Blasting Multimeter

The power cell must be replaced with a type recommended by the manufacturer.

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Only a competent technician may adjust or repair instruments used to test electric detonators or circuits.


Testing a circuit

To test a circuit, press the bare ends of the blasting wire to the terminals of the testing instrument. Then compare the reading with the calculated value; this determines the continuity of the circuit.

Measurement Indication

Within 10% of expected value Circuit okay

No measurement Open circuit or faulty tester

High resistance Poor or loose connection

Low resistance Short, current leakage or caps missing from circuit

Electrical hazards

The minimum firing current necessary to initiate a standard electric detonator is 250 milliamps (0.25 amps). Blasting operations using standard detonators should not be conducted in areas where extraneous current exceeds 50 milliamps (0.05 amps).

Extraneous electricity is undesirable electrical energy that can enter a blasting circuit and cause premature detonation of a detonator.

For a description of equipment and procedures used to test for extraneous electricity at a blast site; and for further advice and assistance, contact the manufacturer or manufacturer’s representative.

A blaster conducting or directing an electrical blasting operation must be able to recognize the following causes of extraneous energy:

Electrical stormsStatic electricityStray currentInduced currentPower transmission linesGalvanic currentRadio frequency energy

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Precautions must be taken to prevent accidental detonation of an electric detonator.


Electrical storms

Electrical storms can generate two hazardous conditions: lightning and static electricity.

Lightning produces approximately 20,000 amps. The electrical energy is capable of travelling great distances through the ground or a conductor, and can cause premature initiation of an electric detonator. If thunder and lightning are present or expected, suspend the blasting operation and keep everybody away from the site until the storm has passed.

Static electricity

Static generated by an electrical storm can accumulate on people, vehicles, or other insulated conductors. It can discharge to ground through the leg wires of an electric detonator, causing it to explode. Instruments are available for detecting the presence of static. In the field, an AM radio tuned to a weak station will produce crackles if static is present. Static is also generated by unfavorable atmospheric conditions, mechanical friction, and pneumatic loading operations.

Atmospheric static can be created by dust storms, snow storms, and low humidity. A Canadian Forces study revealed that under cold, dry conditions the outer surface of a nylon arctic suit held 200 volts, the removal of gloves produced 500 volts, and the removal of a jacket created 5000 volts.

When handling electric detonators in cold, dry conditions, do not wear synthetic clothing. “Ground” yourself whenever possible to discharge static; and do not unravel detonator leg wires by throwing them into the air.

Keep the detonator leg wires shunted; and for additional protection, the ends of the leg wires should be in direct contact with the shell of the detonator until it is ready to be used.

Mechanical static can build up on an insulated conductor. Once interconnecting of detonators has begun, equipment should not be operated.

Mechanical equipment can generate static and must be grounded away from the blasting operation.


Pneumatic loading produces static charges that, if permitted to collect, are capable of initiating an electric detonator. Ground the loading machine and use only semi-conductive hose with approved couplings. Do not place an electric detonator, or liner with any type of detonator, into a hole that is to be loaded pneumatically, unless prior approval has been obtained from WorkSafeBC.

Stray current

Stray current usually refers to electrical discharge from an energized power line. Machinery with faulty grounding or worn wires may be another source of stray current.

Electricity flows to ground via the easiest possible route. If stray current enters a blasting circuit, it could cause accidental detonation.

Stray current is measured using a blasting multimeter connected to a metal stake driven into the ground, and to any metal conductor in the blasting area. The multimeter will indicate if stray current is present.

Should it be necessary to blast near power transmission lines:De-energize the power lineCheck for stray current, orUse a non-electric initiation system

Induced current

Induced current is produced by alternating electromagnetic fields around energized power lines, transformers, and switches. A multimeter can detect induced current.

A detonator can explode if its leg wires touch a conductor and discharge induced currents, or complete an induction loop.

To reduce the potential of induced current, minimize the size of loops in a blasting circuit. Note that bus wires in parallel circuits form a closed loop capable of intercepting induced currents.

•••

To reduce the potential of induced current, minimize the size of loops in a blasting circuit.


Position of Blasting Circuit in Relation to Energized Power Lines

Power transmission lines

Magnetic fields form concentric circles around high-voltage lines. Maximum pickup of induced current results when the line and the loop lie in one plane. Minimum current pickup results when the loop is perpendicular to the high-voltage line.

In addition to generating induced and stray currents, power transmission lines hold a greater danger. Blasting wire in contact with an energized power line poses the danger of electrocution to anyone in the area.

When blasting near power lines, take precautions to prevent wire from being blown across an energized line. Minimize the length of wire in a circuit. Keep blasting wire away from — not parallel to — the power lines; and stake or otherwise secure the wire.

Galvanic current

Galvanic current capable of initiating an elecric detonator is produced when two dissimilar metals (for example, copper and steel) are immersed in an electrolyte (salt water). Alkaline mud in a borehole may react on metallic objects to produce a current that could cause premature initiation.

This is one reason for keeping metal tools and equipment out of the area when an electric initiation system is being used.

Should a wire contact a power line, do not touch or attempt to remove it until the power line has been de-energized.

Maximum Lower Minimum


Radio frequency energy

Radio frequency (RF) energy results from electromagnetic fields produced by RF transmitters, including UHF and VHF television, AM and FM radio, CB and mobile radio, microwave transmissions, and radar. The intensity of RF energy potentially induced in an electric blasting circuit depends on radiated power, distance away, frequency, and wiring layout.

In recent times, RF sources have increased as more and more portable RF devices enter the workplace. Although output of such devices is very low, the threat to safe blasting operations is still present. Examples include:

Handheld cellular phones and wireless devicesWarehousing and inventory management systemsWireless computer LAN systemsRemote equipment control systemsKeyless vehicle entry systemsHandheld 2-way radiosPortable radios in vehicles or equipment

Electrical blasting circuits are not permitted within the minimum distances specified in a standard acceptable to WorkSafeBC. An acceptable standard is SLP 20 of the Institute of Makers of Explosives (IME).

Electrical blasting is not permitted within these minimum distances unless:

The exact type, frequency, and output power of the RF energy transmitter has been identified from manufacturer specificationsThe distance from the blasting circuit to the transmitter is outside the minimum distance specified in a standard acceptable to WorkSafeBC

RF safety precautions

It is unlikely that RF energy will cause accidental initiation of an electric detonator. But in a strong RF field, the leg wires may act as an antenna and absorb sufficient RF energy to initiate a detonator. Shunting or short circuiting a blasting circuit offers little protection if the configuration and orientation of the leg wires are aligned with the RF energy source.

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IntheRegulation

Part 21.61 Radio frequency precautions (1) During electrical blasting, minimum distances from radio frequency transmitters as detailed in Institute of Makers of Explosives, Safety Guide for the Prevention of Radio Frequency Radiation Hazards in the Use of Commercial Electric Detonators (Blasting Caps) Safety Library Publication No. 20, 1988 as amended from time to time, must be maintained. (2) If the minimum distance has not otherwise been determined, electrical blasting circuits are not permitted within (a) 100 m (330 ft) of a CB or other mobile or portable radio frequency transmitter, and (b) 1 000 m (3,300 ft) of an AM, FM, TV, or other fixed radio frequency transmitter.

Blasters' Handbook - ��0 -

When considering using standard or seismic electric detonators:Inspect the area for RF energy transmitters prior to starting a blasting operationEnsure RF energy transmissions are outside the minimum distances specified in the regulations and standards (tables) acceptable to WorkSafeBC Keep mobile transmitters away from the blasting area; post warning signs and, if necessary, have a flag person instruct operators to keep radio transmitters switched offAvoid large loops in the blasting wire by running wires parallel to each other and close togetherIf a loop is unavoidable, keep it small and oriented at right angles to the transmitting antennaKeep blasting wire on or near the ground, with bare connections insulated or sufficiently elevated to prevent current leakageKeep blasting wire out of the beam from directional devices such as radar and microwave relay stations

General safety precautions

Electric detonators carried in a radio-equipped conveyance must be placed in a closed metal container, electrically bonded to the conveyance, and lined with wood or other material such as rubber or felt. Leg wires must be kept folded and shunted. Radio transmitters in proximity to the container must be switched off whenever it is open.Keep electric detonators short-circuited until wired into the blasting circuit. The shunt may be removed temporarily to test the detonator.Hold the detonator leg wires to the side of the hole during loading, tamping, or stemming.Ensure wire used in a blasting circuit is capable of transmitting the required current.Protect bare connections in a blasting circuit from contact with conductive material and the ground.Except for testing, keep each series of electric detonators short-circuited until the time of detonation.Before firing any electrical blasting circuit, use a blasting galvanometer or multimeter (of a design acceptable to WorkSafeBC) to test the resistance of each series and the complete circuit.Do not fire any electrical blast unless the test reading corresponds to the calculated resistance for each series and the complete circuit.

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Take precautions to prevent accidental detonation of electric detonators from any source of electricity.


Use a blasting machine in good condition, of a type acceptable to WorkSafeBC.Do not use a dry or wet cell storage battery, such as a flashlight or a truck battery, to fire an electric detonator.Test the blasting machine, using methods specified by the manufacturer, on a regular basis and before any blast requiring the maximum output of the machine.Keep the blasting machine isolated from and disconnected from the blasting circuit until the blast is ready to be fired.Do not exceed the firing capacity (rated capacity) of the blasting machine.

Standard electric detonator

The standard electric detonator (blasting cap) is an initiating device capable of detonating most high explosives. It has an aluminum shell approximately 6 mm (1/4 in) in diameter, varying in length from 33 mm (1 1/4 in) for an instantaneous detonator to 100 mm (4 in) for a detonator with a long delay period.

Pressed into the base end of the shell is a composite charge of heat-sensitive lead styphnate, the primary charge, and a high explosive, PETN (pentaerythritol tetranitrate).

Two insulated leg wires enter the shell through a rubber plug, which holds them in position and forms a water-resistant seal.

The leg wires terminate in a “bridgewire” embedded in an ignition charge. When a minimum amount of current is passed through this filament, it becomes very hot, igniting the primary charge, which detonates the base charge of PETN.

Standard Electric Detonator

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BaseCharge Primer

Charge

PlasticCup BridgeWire&

RubberPlugAssemblyInsulatedLegWires

Anti-StaticGroove


Electric detonators have a “static short” built in for protection against static charges. Each leg wire has a triangular compression slightly ahead of the second crimp known as the “anti-static groove.”

The static short is designed to drain off static charges from the leg wires to the anti-static groove before they enter the bridgewire and cause detonation.

Leg wires

Leg wire is a solid metal conductor, usually made of copper — a good conductor of electricity. Iron wire is used in operations where foreign materials are removed from blasted rock by magnetic separation.

The wire is coated with a layer of tin and covered with flexible plastic insulation, resistant to abrasion. Standard electric detonators are available with 22 gauge leg wires in a number of common lengths.

Detonator types

Instantaneous detonators contain no delay element. Application of the electrical current and initiation of the detonator are virtually simultaneous.

Short period (SP) delay detonators have delay elements, measured in milliseconds (ms) between the ignition charge and the base charge.

Short period detonators are commonly used in surface blasting operations. When used properly, they offer the following advantages:

Minimize cutoff holesReduce vibration and concussionImprove fragmentationProduce predictable amounts and throw of muckReduce backbreak and overbreak

Long period (LP) delay detonators have a slow delay element between the ignition charge and the base charge. Delay periods are available with an average of 500 ms (0.5 sec) between each period. They are used in underground and surface operations where greater delay times are necessary to permit relief for firing the next charge.

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Standard Electric Delay Detonator

Shunt

All standard electric detonators have a metal foil “shunt” on the ends of the leg wires, which joins them together. This keeps them clean and forms a short circuit capable of protecting the detonator from stray current.

Once removed, it may be difficult to replace. The detonator can also be shunted (short circuited) by twisting the bare ends of the leg wires together.

Electronic detonator

There are several electronic detonating systems being used and tested in the explosives industry today. These electronic systems offer timing accuracy not previously achieved.

The other detonating systems in use today (electric detonators, detonating cord relays, shock tube assemblies, etc.) rely on a pyrotechnic delay element. These pyrotechnic elements cannot be manufactured to achieve the precision timing that is sometimes required for large, critical blasts. The phenomenon known as “cap scatter” sometimes results in an overlap of the actual firing of different periods. The electronic detonator relies on electronic circuitry for timing; thus the timing of these detonators is very precise.

Shunt

Do not remove the shunt until the detonator is connected into the blasting circuit.


There is also considerable difference in the equipment, blasting machines, connectors, and procedures that would be employed to hook up and fire the blast. Standard electric or non-electric donating systems can be fired using generic blasting machines. However, electronic systems must use blasting machines and accessories designed specifically for each manufacturer’s detonators.

There are two basic categories of electronic detonator systems:Factory programmed systemsField programmed systems

Factory programmed systems use a “fixed” delay. Generally, the holes are loaded and hooked up in the same way as a standard electric or shock-tube system. Although the detonators, the wiring, and the procedures may appear to be similar to standard electric blasting, the user must always consult the manufacturer for specific procedures.

Field programmed systems offer great flexibility. With these systems, the blaster is able to program the delay in each detonator. The programming may take place before the detonators are loaded, after the detonators are loaded, or immediately prior to firing.

The blasting machines, the equipment, and the detonators are all unique to a specific manufacturer. The blaster should never mix the components of one system with the components of another system. Above all, the procedures for design, hook up, and firing are specific to the system being used.

Blasting machines

A blasting machine is a current-producing device used to initiate an electrical blast. Most blasting machines are small and portable. There are two types of blasting machines: generator and capacitor discharge — both will produce electrical energy with sufficient amperage and voltage to “fire” the number and type of detonators for which it is rated.

Generator: A rackbar or twist spindle rotates the armature of a small generator that, upon reaching full capacity, automatically releases the current.Capacitor discharge: By depressing a button or a switch, a high voltage charge from a dry cell battery builds up on a bank of condensers. A glow light indicates full charge. When the firing button is pressed, the current discharges from the capacitor.

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The blaster should never mix the components of one system with the components of another system.


Capacitor discharge machines are also available in multi-circuit models, where each series can be wired separately and fired with very precise electronic delay between circuits. These are known as sequential blasting machines.

50-shot 10-shot 200-shot 50-shot Push-down Twist Condenser Condenser

A blasting machine must have its firing capacity clearly marked on it. All machines designed and manufactured specifically for firing electric detonators are acceptable to WorkSafeBC. The label must indicate the maximum number of electric detonators that can be initiated in a single series, a series-in-parallel, or a parallel circuit; this is known as the “rated capacity” of the blasting machine.

The rated capacity of most blasting machines is only valid for certain types of electric detonators, and for detonators and blasting wire of a specific resistance. In all cases, the manufacturer’s specifications must be adhered to.

Blasting machines must be maintained in good condition. Do not make repairs or adjust them at the work site. They should be serviced only by competent technicians, and the power cell of a condenser discharge blasting machine must be replaced with a type recommended by the manufacturer.

Precautions must be taken to prevent a premature blast. Keep the machine in a safe, secure location until immediately before use.

When connecting the circuit to a “push-down” machine, the rackbar must be in the “down” position, requiring a deliberate up and down movement to fire the blast.

Do not attempt to fire a blast when the power requirements of the electrical blasting circuit exceed the rated capacity of the blasting machine.


A dry (flashlight) or wet (car) battery must not be used. The power output from such batteries is unreliable, and a misfire could result. They have exposed terminals; and should the firing cables inadvertently touch them, an accidental (premature) detonation will occur.

Circuit configurations

A standard electric detonating system uses one or more standard electric detonators wired into single series circuit and series-in-parallel series circuit.

Single series circuit

A single series circuit has one or more electric detonator(s) connected into one series. The total number of detonators in a single series circuit must not exceed the rated capacity of the blasting machine.

The following diagrams illustrate typical single series circuits having 1, 5, and 10 detonators respectively. In the diagrams, “0” represents an electric detonator, and they are joined together by lines representing blasting wire.

Various Single Series

A single series circuit may be interconnected (wired up) in patterns other than those indicated. However, it must include every detonator and should be laid out in a tidy configuration.

Single series calculations

The resistance for each series, and the complete circuit, must be calculated. To do so, blasters must know:

The number and type of detonatorsThe length and type of blasting wire

All calculations should follow a simple format. To calculate the resistance for a single series circuit, refer to the proper resistance table (see Appendix 4) for:

The type of detonator

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Diagram1 Diagram2 Diagram3


The type of leg wire (copper or iron)The length of leg wire

Determine the resistance of each detonator connected into the single series.Add the resistance of all the detonators in the series.If all detonators have the same type and length of leg wires, multiply the resistance of one detonator by the total number in the circuit.Determine the resistance of all blasting wire used in the circuit.Duplex wire has two (2) separate wires in a protective covering. Double the given length of duplex wire to obtain the total length of lead wire in the blasting circuit (for example, 500 feet of duplex wire = 1000 feet of wire)Total resistance = the resistance of all detonators plus the resistance of all blasting wire.

Tables for electric resistance of wire and detonators are found in Appendix 4. Examples of single series electrical calculations are also found in Appendix 4.

Testing the circuit

Each series and the complete circuit must be tested with a galvanometer or blasting multimeter. Once all the detonators are connected into a series, test the series before connecting the blasting wire. Some blasters prefer to test the blasting wire separately before connecting it to the circuit. For a single series, it is only necessary to test the completed circuit.

The testing device must itself be tested prior to use. Touch a short length of wire to both terminals, and the galvanometer should indicate a resistance reading between 0 and 1 ohm. A high reading, or no movement of the needle from infinity (∞), indicates the galvanometer is damaged, out of adjustment, or the power cell must be replaced.

Re-check the testing device (as described above).Re-check the calculations.Re-check the blasting circuit.

If the test reading does not coincide with the calculated value, do not attempt to fire the circuit until the problem has been corrected.

A testing instrument connected to a blasting circuit will indicate the possible source of the problem.

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The blast must not be fired unless the test readings coincide with the calculated resistance for each series and the complete circuit.

Test the complete circuit by touching the bared ends of the blasting wire to the terminals of the galvanometer or blasting multimeter. The reading should be within 10 percent of the calculated value for the complete circuit.


Measurement ProbableCauseNo measurement Open (broken) circuitHigh resistance Poor or loose connectionLow resistance Short, current leakage or caps missing from circuit

A detonator or section of blasting wire is tested by touching the bare wire ends to the terminals of the testing instrument. Each detonator or section of blasting wire may be tested individually. It is unnecessary to disconnect individual detonators from a circuit, as the instrument only measures the resistance in the portion of the circuit between its terminals.

When a circuit contains numerous detonators, it may be easier to locate a fault using the following procedure.

Attach a length of blasting wire to an open end of the circuit. Hold the end of this wire to a terminal on the galvanometer, and then touch the other terminal to bare connections throughout the circuit. This allows the circuit to be divided into smaller areas until the fault is located. After correcting a fault, test the series and circuit again. There could be more faults.

Using a Galvanometer to Locate a Fault in a Blasting Circuit

Series-in-parallel circuit

A series-in-parallel circuit may be thought of as two or more single series circuits joined together into one circuit. The resistance (in ohms) of each series in the circuit MUST be balanced.

Many blasters balance their series by placing the same number of detonators in each one. Often, extra detonators are added to balance one series with the others.

Because electricity takes the path of least resistance, each series must have approximately the same resistance; otherwise, a hangfire or misfire may occur.

123456

CB

A


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The number of series in a series-in-parallel circuit is only limited by the rated capacity of the power source. Two series-in-parallel, or “double” series, are quite common.

The following diagrams illustrate typical circuits having two, three, and four series-in-parallel. Each series contains four detonators.

Series-in-parallel calculations

The resistance for each series and the complete circuit must be calculated. Calculations must include the:

Number and type of detonators in each seriesNumber of seriesLength and type of blasting wire

To calculate the resistance of a series-in-parallel circuit, follow the procedures for a single series circuit. There is, however, one significant difference:

Each series provides a separate path for the electrical current; thus, the resistance of the circuit decreases as more series are connected to it. When the series are balanced, the total resistance of a series-in-parallel circuit equals the resistance of one series divided by the number of series in the circuit.

This is explained in the following example. Assume there are a number of series of electric detonators, with each series having a resistance of 12 ohms. As more series are connected into the series-in-parallel circuit, the total resistance of that circuit is reduced in the manner indicated.

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Diagram1 Diagram2 Diagram3


NumberofSeriesintheCircuit TotalResistanceoftheCircuit1 series 12.0 ohms2 series 6.0 ohms3 series 4.0 ohms4 series 3.0 ohms5 series 2.4 ohms6 series 2.0 ohms

It is important to keep the resistance of each series balanced. If not, more electrical current will flow through the series with the least resistance.

Unbalanced series make it difficult to calculate and test the resistance of the complete circuit with conventional techniques and equipment.

Sequence

Calculations for a series-in-parallel circuit should be performed as follows:

Determine the resistance (ohms) of each detonator.Calculate the resistance of all detonators connected in a single series.Calculate the resistance of all detonators that are connected into the series-in-parallel circuit. (To calculate the resistance of a series-in-parallel circuit, divide the resistance of one series by the total number of series in the circuit.)Determine the resistance of all blasting wire used in the circuit.Calculate the total resistance of the complete circuit (total resistance = the sum of steps 3 and 4).

Note: Examples of series-in-parallel calculations are shown in Appendix 4.

Testing the circuit

With a galvanometer or blasting multimeter, test each series individually before connecting it into a series-in-parallel circuit. Unless each is tested, the final circuit test may fail to reveal faults in a series.

Record the test reading for each series. Because many instruments are not completely accurate, identical readings may be impossible, but they should be within 10 percent of each other.

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A series with higher resistance could experience hangfires or misfires because of insufficient current.


The greater the difference in resistance between series in a circuit, the greater the likelihood of a hangfire or misfire. This is particularly true if the blasting machine is weak or the circuit is close to the rated capacity of the machine.

If the test reading does not agree with the calculated value, locate and correct the problem before connecting into the circuit.

After all series are connected, a test reading of the complete circuit is unlikely to reveal a problem within a particular series. A faulty connection or break in one series may not be detected by a test of the complete circuit. It is therefore necessary to visually check any series-in-parallel circuit before firing the blast.

Power line blasting

Power line blasting uses a high voltage power source to initiate an electrical blast. This can be an electrical generator (not a blasting machine) or a power line.

Firing from a power line is more complex than using a blasting machine, which has built-in safeguards; and if well maintained, the blaster need only keep the circuit within the “rated capacity” of the machine.

For power line blasting, the necessary amperage and voltage must be calculated. In addition to using an acceptable blasting switch, precautions must be taken to prevent unwanted current entering the circuit, causing premature detonation.

Amperage

Power line current is usually alternating current. A minimum of 1.5 amps (or 2.0 amps AC) is required for each series of standard electric detonators, in a series or series-in-parallel circuit.

Voltage

The power source must have the necessary voltage to reliably initiate all detonators in a circuit. To calculate this voltage, apply Ohm’s Law. Ohm’s Law states, “voltage equals current (amps) multiplied by resistance (ohms)” and is expressed as: E = I x R

Do not attempt to fire a blast if the difference in resistance readings between series exceeds 10 percent.

A minimum of 1.5 amps is required for each series in a circuit.


For simplicity, in this manual the formula is expressed as: V = I x R

Where V = Voltage (in volts) I = Current (in amperes) R = Resistance (in ohms)

Once the total resistance (ohms) and total required current (amps) have been determined, multiply them to calculate the voltage. Then verify that the power source can reliably initiate the blasting circuit.

Ohm’s Law triangle

The Ohm’s Law triangle is a memory aid for Ohm’s Law. Where: V = volts I = amps R = ohms

Place a finger over one symbol; then multiply or divide the remaining symbols according to their relative position in the triangle. For example, cover V and it equals I multiplied by R. Cover I and it equals V divided by R.

So, V = I x R and I = V R

Power line calculations

Electrical calculations for series and series-in-parallel circuits should be performed as follows:

Determine the resistance (ohms) of each detonator (use the proper resistance table).Calculate the resistance of all detonators connected into each series.

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V

I R


If there is more than one series, calculate the equivalent resistance of the series-in-parallel (resistance of one series divided by the number of series).Determine the resistance of all blasting wire in the circuit.Calculate the total resistance of the circuit.

Total resistance = the sum of steps 2 and 4 for single series OR sum of steps 3 and 4 for series-in-parallel

6. Determine the minimum current (amps) needed to fire the blast. A minimum 1.5 amps is required for each series of standard

electric detonators in a single series or series-in-parallel circuit.7. Calculate the voltage required to detonate the blast.

Examples of power line blasting calculations are shown in Appendix 4. Testing of power line blasting circuits is as previously described under Single series circuits and Series-in-parallel circuits.

Blasting switch

An electrical blast must not be fired from a power line or electrical generator unless the flow of current is controlled by a blasting switch acceptable to WorkSafeBC. A typical blasting switch comprises three units: a fuse box, a firing box, and a short circuiting box. It may also consist of several independent switches.

The fuse box is a metal box containing fuses and a main switch. It is grounded to protect the operator and minimize the effects of lightning. This box should be kept locked in the “off” position.The fuses are to protect the power source from overload if a short circuit occurs at the time of firing. The main switch controls the flow of electricity from the power lines to the firing box.The firing box is made of wood or other nonconductive material. It has a pilot light (to indicate the presence of current) and a firing switch (handle). Some boxes have a voltameter and a gravity switch that will automatically short-circuit and isolate the blasting circuit.The cable from the firing box should not be connected to the fuse box until immediately prior to firing the blast.The short circuiting box consists of an insulated panel with one or more switches to control and protect the individual blasting circuits. These switches, which should be kept locked in the short-circuited position until the blast is ready to be fired, are usually the double-throw, non-fused type.

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•The cable from the firing box should not be connected to the fuse box until immediately prior to firing the blast.


Elements of a Typical Blasting Switch

Blasting switches are to be kept insulated from the ground or any other source of stray current.

During an electrical blasting operation, the blasting switch must be kept inaccessible to all persons except the blaster. It must also be isolated from the circuit until the blast is ready to be fired.

Unlike the fuse box, the firing box and short circuit box must not be grounded.

PowerMains

Main(doublepole)SwitchShorting

Bar

Ground

MetalCase

FusesReceptacleforShortCablefromFiringBox

1.FUSEBOX

Plug-inConnectortoFuseBox

WoodenBox

PilotLampFiringSwitch(doublepole)ShortingBar

ToShortCircuitingBox

CablefromFiringBoxWoodenBoxSwitch(doublepole)

FiringLinetoFace

ShortingBarwhenSwitchisintheOffPostion

3.SHORTCURCUITINGBOX

2.FIRINGBOX

Appendices


Appendix 1: Supplemental Resource References

Explosives ActThe Explosives Act and Regulations are subject to revision, and blasters must always be aware of the latest requirements. Up-to-date information is available on the Natural Resources Canada web site www.nrcan.gc.ca/mms/explosif/index.htm.

Explosives informationVendors are the best source of up-to-date information on explosives. Many vendors maintain web sites that have current and detailed information. Some sites are:www.dynonobel.com www.austinpowder.com/home.htm

Explosives safetyGeneral and safety information on explosives can be obtained through the Institute of Makers of Explosives web site www.ime.org.

Explosives tools and equipmentCompanies supplying blasting tools and equipment frequently have web sites, for example www.researchenergy.com and www.idealsupplyinc.com.

International Society of Explosives Engineers and blasting handbooksHandbooks on explosives and blasting can be obtained through the International Society of Explosives Engineers. Their web site and the “Blaster’s Library” can be accessed at www.isee.org/. The Western Chapter of ISEE can be accessed at www.iseewest.org/.

Transportation of Dangerous Goods Act and RegulationsThe Transportation of Dangerous Goods Act and Regulations are subject to revision, and blasters must always be aware of the latest requirements. Up-to-date information is available on the Transport Canada website www.tc.gc.ca/tdg/.


Appendix 2: Glossary of Blasting Terms

Air Blast The airborne shock wave from a blast

AmEx A factory mixed blasting agent containing AN prills, oil, and an orange dye

Amp A unit of electrical current; produced by 1 volt flowing through a resistance of 1 ohm; also known as “ampere”

AN Ammonium Nitrate; the oxidizer in a nitrate mixture explosive

AN/FO Ammonium Nitrate/Fuel Oil; a blasting agent, blended at the loading site under the provisions of a permit or licence issued by the Explosives Branch (Canada)

ANSI American National Standards Institute

Anti-static Groove

The indentation (groove) in the shell of a detonator at the open end; serves to drain static electricity from the “static short”

Assembly A detonator attached to a length of safety fuse or non-electric shock tubing

Assistant A person who assists the blaster in preparing, placing, and firing a charge or in handling a misfire; also known as a helper

Attended By The physical presence of a competent person in visual contact with and with control over explosive materials

AWG American Wire Gauge; a standard for measuring the diameter (gauge) of wire

Backbreak The area of breakage occurring behind the last row of blast holes

Base Charge The main explosive charge in the base of a detonator; usually consists of PETN

Black Blasting Powder

See Gunpowder


Blast A method of bonding, loosening, moving, or shattering materials using explosives through detonation of a charge; creating a detonation wave and gas pressure

Blast Hole A hole loaded with an explosive charge

Blast Site A site where a blast has occurred; may also refer to a site where a blast is about to occur

Blaster The person who conducts or directs a blasting operation; the holder of a valid blaster’s certificate issued by WorkSafeBC

Blasting Accessories

Non-explosive devices and materials used in a blasting operation, including but not limited to blasting machines, crimpers, galvanometers, lead wire, loading poles, and tamping rods

Blasting Agent An explosive that meets prescribed criteria for insensitivity to initiation (meaning insensitive to a high strength detonator); includes many nitrate mixture explosives

Blasting Area An area extending at least 50 metres (165 ft) in all directions from any place in which explosive materials are being prepared or placed, or in which an unexploded charge is known or believed to exist

Blasting Cap A common term for a plain detonator

Blasting Circuit The circuit, consisting of blasting wire, used to fire one or more electric detonators (see Blasting Wire)

Blasting Log The written record of loading details and examination of the site after a blast

Blasting machine

An electrical or electromechanical device that produces current from a generator or condenser discharge device; used to initiate an electric detonator; also known as an “exploder”

Blasting mat An interconnected device to cover a blast and control fly material; usually made of woven wire cable, posts, or tires


Blasting multimeter

A testing instrument containing a special power cell and resistors to control current output; measures resistance in ohms and current in volts and millivolts

Blasting Operation

Includes preparing, placing, and firing a charge; handling a misfire; and destroying any explosive materials

Blasting Switch A device used to control the flow of electricity from a power source to the blasting circuit

Blasting Wire Lengths of wire that conduct electrical current through a blasting circuit; may be bare or insulated; the term includes bus wire, connecting wire, firing cable, and lead wire

Blow Pipe A hollow pipe used to direct compressed air into a bore hole to clean it out prior to placing the charge; may also be used (with water) to remove stemming after a misfire, for the purpose of refiring; not to be used to remove detonators or explosives

Booster An added explosive to intensify the reaction of a detonator or detonating cord; used to initiate explosives that are insensitive to normal initiation

Bootleg A common term for the socket of a blasted hole

Bore Hole A drilled hole that does not yet contain explosive materials

Bottom Prime The act of placing the primer at or near the bottom of a blast hole

Branchline A length of detonating cord or tubing used to connect downlines (pigtails) in a row of loaded holes; usually attached to a main trunkline

Bridgewire A wire filament imbedded in an electric detonator to which the leg wires connect

Bulk Loading The act of loading AN/FO, slurry, or emulsion by means of a mix or pump truck


Burden The volume of material blasted by a charge; the distance between the blast hole and the nearest free face; also known as “burden distance”

Bus Wire Blasting wire used to connect electric detonators into parallel or series-in-parallel circuits; usually bare copper wire (14 gauge)

CB Citizen’s Band

Cap A blasting cap; common term for detonator

Cap Box A box for keeping detonators; see Detonator Box

Cap-sensitive An explosive material that will detonate when the material is unconfined

Capwell A pre-formed cavity in a cartridge or booster designed to accept a detonator

Cartridge A rigid or semi-rigid unit of high explosive manufactured and wrapped to a predetermined length and diameter; also known as a “stick” or “sausage”

Cast Booster A preformed high explosive (such as pentolite) used to initiate non-cap-sensitive explosives; not really a primer until it is armed with a detonator or other initiating device

Charge Explosive materials that have been prepared, placed, and are ready for detonation; may not contain a primer

Collar The open end of a bore hole; also refers to the unloaded portion of a blast hole

Collar Distance The distance from the top of the explosive column to the collar of the blast hole; usually filled with stemming material

Collar Prime The act of placing the primer at or near the opening of a blast hole


Column Charge A continuous column of explosives in a blast hole; also, a continuous section of low energy explosives placed above a section of high energy explosive in the toe of a hole (“toe load”)

Competent Adequately qualified and capable of performing assigned duties; one who by reason of training, instruction, and experience is able to safely perform assigned work with no or minimal supervision

Capacitor Discharge Blasting machine

A blasting machine that uses batteries or generator to energize one or more capacitors; the stored energy from which can be released into a blasting circuit

Conductor Any material that allows a continuous current to flow through it when a voltage is applied; a wire, cable, or other form of metal installed for the purpose of conveying electric current

Connecting Wire

Blasting wire used to connect electric detonators into a blasting circuit; usually insulated copper wire (18 to 20 gauge)

Connector A plastic device used to attach a detonating cord or tubing to trunkline

Container A fully enclosed, locked, secure receptacle designed and used for temporarily keeping or transporting explosive materials

Continuity The integrity of a blasting circuit; a measure of whether a circuit is complete (unbroken) or not

Conveyance Includes an aircraft, watercraft, or motor vehicle used to transport explosive materials

Core Load The explosive core of detonating cord; grams per metre (grains per foot) of PETN in the cord

Crimp The circular depression at the open end of a detonator that secures the safety fuse or leg wires in place


Crimper A special, non-sparking tool for cutting safety fuse and for attaching a plain detonator or igniter cord connector to a fuse

Cross-tie A length of detonating used to provide an alternate detonation path in the circuit; serves to prevent a cut-off

Current The flow of electricity in a blasting circuit; measured in amps (amperes)

Cut-off A type of misfire; usually refers to damage to or isolation of explosive materials (charge) resulting from ground movement

Danger Any matter, thing, condition, or situation that could inherently cause injury or illness to a person exposed thereto

Danger Area Any area in which there may be a danger to any person from fly material or other condition resulting from a blast

Day Box An unlicensed magazine (constructed to Type 6 specifications), not used for overnight storage; a form of container

DC Direct Current; the flow of electrical energy in one direction

Dead Press The desensitization of an explosive due to increased critical density caused by pressurization; compression of a blasting agent in a blast hole, resulting from shock waves produced by an adjacent detonation; may require a booster to ensure initiation

Deck Charges Separately primed charges in a common hole; usually separated by a spacer or stemming material

Decking A method of loading in which a spacer or stemming material is placed between deck charges in a blast hole


Deflagration The propagating thermal decomposition of an explosive at a subsonic velocity less than 915 m (3000 ft) per second); a reaction that occurs in a low explosive; distinct from detonation

Delay Blasting The practice of using a delay element device (detonator or detonating connector) to delay the detonation of an individual or group of charges; see Sequential Blasting

Delay Element In a delay detonator, a composition that produces the predetermined time delay between initiation and detonation

Delay Tag A tag, band, or marker attached to a delay element detonator that identifies the nominal firing time

Density The mass of an explosive per unit of volume; usually expressed in grams per cubic centimetre or pounds per cubic foot

Deterioration The chemical breakdown of an explosive

Detonating Cord

An explosive core of PETN contained in a flexible waterproof covering; initiated by a detonator; explodes at over 6705 m (22,000 ft) per second; initiates most explosives in contact with it

Detonation A supersonic explosive reaction that propagates a shock wave through the explosive, accompanied by a chemical reaction that furnishes energy to sustain the shock wave propagation in a stable manner; refers to the explosion that occurs in a high explosive; distinct from deflagration

Detonation Wave

The initial shock (shattering) wave that results from the detonation of a detonator or charge; the effect is known as brisance; the speed of detonation is referred to as VOD

Detonator A blasting cap used to initiate detonation in an explosive; a small metal tube containing a sensitive primary charge and PETN; includes electric and non-electric blasting caps


Detonator Box A crush-resistant container used for protecting detonators at a loading site; also known as “cap box”

Double Prime The procedure of attaching two detonators to a primer or a detonating cord; offers protection against a misfired charge

Down Hole A vertical or near vertical hole that is drilled (and loaded) from above

Downline A length of detonating cord or plastic tubing, in a blast hole, that transmits energy from the trunkline to the charge

Duplex Wire Two separate lengths of blasting wire contained in a common protective covering; distinct from simplex wire

Dynamite A type of high explosive containing NG

Electric Detonator

A detonator designed to be initiated by an electric current

Electrical Storm

An atmospheric disturbance of intense electrical activity that increases danger during blasting activities; includes lightning

Electrolyte A non-metallic electrical conductor through which a current is carried by the movement of ions between the electrodes

Emulsion An explosive produced through the interaction of a dissolved oxidizer and fuel in the presence of a chemical emulsifier; water resistant

Exploder A common term for a blasting machine

Explosion A rapid chemical reaction producing high temperatures and (usually) a shock wave and large volume of gases

EOD Explosive Ordinance Disposal; a branch of the military concerned with disposal of explosive materials


Explosive A chemical compound or mixture, the primary or common purpose of which is to function by explosion; initiated by fire, friction, concussion, percussion, or detonation; produces a sudden release of gases having a pressure capable of destructive effects; usually refers to commercial explosives and includes a blasting agent

Explosive materials

Includes explosives, blasting agents, and detonators

Extraneous Electricty

Any unwanted electrical energy that may enter a blasting circuit or detonator; can result in premature detonation; sources include galvanic action, induced and stray current, lightning, radio frequency, and static electricity

Face A (rock) surface that has been drilled, loaded, or blasted; usually refers to a vertical surface

Fault An abnormality in the material to be blasted; including cavities, joints, planes, seams, and slips; usually requires a special loading technique for a blast to have the desired effect

Fines Drill cuttings (residue) from a bore hole; undersize material of little value produced by a blasting/crushing operation

Firing The act of setting off (detonating) a charge

Firing Cable A blasting wire, often permanent, extending from a blasting machine to the circuit of electric detonators; usually 12 or 14 gauge copper wire

Firing Line A common term for blasting wire; sometimes used in place of "Firing Cable"

Flammable material

Includes any fuel, paper, rag, or other similar material that is readily combustible and may cause or spread fire or explosion

Flash Over Propagation between charges or between loaded blast holes


Fly material Material that is thrown (projected) by the force of a blast; includes dirt, ice, metal, rock, and wood; may be dangerous and is generally undesirable

Flyrock A type of fly material

Fracturing Breaking or cracking of material (rock)

Fragmentation The extent to which material (muck) is broken or reduced in size; an estimation of average diameter

Fuel Oil The fuel used in AN/FO; usually No. 2 diesel fuel

Fumes The noxious or poisonous gases from detonation of an explosive; includes carbon monoxide and oxides of nitrogen

Fuse A common term for safety fuse

Fuse Lighter A pyrotechnic device for rapid and dependable ignition of safety fuse

Fusee A safety match with an enlarged head; used to ignite a safety fuse assembly

Galvanic Action

The action of an electrolyte on dissimilar metals; a battery-like reaction; produces electric current

Galvanometer An instrument used to measure the resistance of blasting wire, electric detonators, and blasting circuit. Galvanometers, ohmmeters, multimeters or noltmeters must have the words “Blaster” or “Blasting” on their label

Gauge A measurement of the diameter (thickness) of a wire

Gelatin An explosive that has a gelatinous consistency; generally contains NG and nitrocotton

Generator Blasting machine

A blasting machine operated by vigorously pushing down a rack bar or twisting a handle


Grain A measurement of weight; there are 15,400 grains in a kilogram and 7,000 grains in a pound

Ground An electrical connection to earth

Ground Vibration

Shaking of the ground caused by the shock waves from a blast

Guard A person posted for the purpose of guarding a blast

Guarding The act of preventing entry to a danger area; also refers to protecting explosive materials or charges from tampering or theft

Gunpowder A low explosive consisting of sulphur, carbon, and potassium or sodium nitrate; used in safety fuse; also known as black powder or blasting powder

GVW Gross Vehicle Weight; the rated capacity of a vehicle

Hangfire A type of misfire; an undesirable delay in the detonation of a detonator or explosive; generally resulting from arcing, or damage to safety fuse, detonating cord, or detonator; may involve burning (smoldering) of the fuse, detonator, or explosive; a very dangerous condition as it could detonate at any moment

Helper A common term for assistant; may also refer to a type of “relief” hole in a cut

High Explosive

An explosive in which detonation will occur; develops high gas pressures and a significant detonation wave

High Strength Refers to any detonator having 0.78 gm (12 gr) or more of PETN, or the equivalent energy output

Hook-up The procedure of interconnecting detonating cord or detonators in preparation for firing a blast; referred to as “wire up” in electrical blasting operations

Hot Wire Lighter

A sparkler device used to ignite one or more safety fuse assembly; also known as “fuse lighter”


Hydrostatic Head

Water pressure; specifically, the pressure on explosive materials that results from water above it in a hole

Ignite The act of setting fire to safety fuse or any flammable material

Igniter Cord A small diameter wire coated with incendiary composition that burns intensely; used to ignite a series of safety fuse assemblies; attached to an igniter cord connector; available in fast, medium, and slow burning speeds

Igniter Cord Connector

A metal tube containing incendiary composition; crimped to one end of a safety fuse assembly; with a clip to hold the igniter cord in position

ImE Institute of Makers of Explosives; a safety association concerned with safety in respect to manufacturing, transporting, storing, handling, and using commercial explosive materials

Initiate The act of detonating an explosive or an initiator (detonator)

Lead Azide A type of primary explosive in a detonator

Lead Styphnate A type of primary explosive in a detonator

Lead Wire Blasting wire extending from the power source to the electric detonators; usually 12 or 14 gauge insulated copper wire

Leg Wire Insulated wire attached to the bridgewire of an electric detonator; usually 20 or 22 gauge copper or iron wire; the bare ends are “shorted out” by means of a shunt

Limiting Cord Distance

A rule for calculating the maximum length of igniter cord; equals the length of fuse inside the hole multiplied by the speed factor of the igniter cord being used


Liner A plastic “sock” used in a blast hole to protect the explosive (usually a blasting agent) from moisture and other contamination

Loading The act of placing explosive materials into a blast hole

Loading machine

A device for pneumatically loading nitrate mixture explosives

Loading Pole A pole made of non-sparking material; used to place explosive materials in a blast hole; may also be used to check depth of the hole, clean the hole before loading, and tamp explosives in the hole

Loose Unstable material (rock) likely to collapse or fall; can result from the shock waves of a blast; evident in backbreak and conditions

Low Explosive An explosive capable of deflagration and low gas pressure; includes gunpowder

LP Long Period; a category of delay in a detonator

magazine A structure used to store either detonators or explosives; a building or other structure meeting the regulations and standards pursuant to the Explosives Act (Canada); may be either licenced or unlicenced; distinct from Suitable Receptacle

maximum Firing Current

The maximum current (amperage) recommended by the manufacturer for effective performance of an electric detonator

misfire A charge or part of a charge that, upon initiation, failed to completely detonate; causes include arcing, cut-off, and damaged or deteriorated explosive materials; a dangerous condition

mishole A hole containing explosive materials that failed to completely detonate


mHz MegaHertz; a unit of frequency equal to 1,000,000 cycles per second

ms Millisecond; a thousandth of a second

ms Connector See Detonating Connector

muck Broken material (rock) resulting from a blast

mud Capping A method of secondary blasting or boulder breaking; a charge is placed on a boulder and covered with material (mud, sand) to confine the gases; also called plaster shooting

NG Nitroglycerin; a clear, oily explosive used as a sensitizer in dynamite; very sensitive in its liquid form

Non-sparking A device or material that will not readily produce a spark when struck against a hard surface

NOTAm Notice To Airmen; a notice issued by Transport Canada to aircraft pilots

Ohm A unit of electrical resistance

Ohm’s Law E=IR; voltage equals current (amps) multiplied by resistance (ohms); used to calculate the voltage required to fire an electric blasting circuit

Overbreak Excessive breakage of rock beyond the desired excavation limit

Overbreak Control

A method of firing perimeter blast holes so as to avoid backshatter; intended to preserve a smooth, stable face; techniques include cushion blasting, line drilling, and pre-shearing

Overburden Material (dirt, gravel, shale) lying on top of a deposit of useful material


Oxidizer An ingredient in an explosive that supplies oxygen, which combines with the fuel to form gaseous or solid products of detonation; AN is a common oxidizer

Parallel Circuit A circuit in which the leg wires from each electric detonator in a circuit are connected to bus wires on opposite sides of the blasting circuit

Pattern A dimensional plan of bore holes; a description of the location of holes in relation to each other and a free face; usually includes burden and spacing dimensions

Pentolite An explosive consisting of PETN and TNT; commonly found in a booster

PETN Pentaerythritol Tetranitrate; a white crystalline powder of high explosive used as the core load in detonating cord and the base charge of a detonator

Piggy-back An initiation technique where one shock tube assembly is used to initiate another or several other shock tube assemblies; the connection is made with a plastic “bunch block” device

Pig Tail The length of detonating cord or plastic tubing that protrudes from a loaded hole; the outer portion of a downline; also refers to the length of detonating cord attached to a pigtail detonating connector

Pneumatic Loading

Placing an explosive, usually a blasting agent, using compressed air

Powder General term for any commercial explosive

Powder Factor The amount of explosive used per unit of material; usually expressed as kilos per cubic metre (lbs/cubic yard) or the tons of material per kg (lb) of explosives; also known as “loading factor”

Powder Headache

A type of headache induced by exposure to NG; blood vessels dilate (expand) and allow an excess of blood to press on nerves in the head


Powder Punch A non-sparking instrument used to punch a hole in a cartridge; usually made from a 6 mm (1/4 in) diameter brass or copper rod, pointed and fitted with a handle

Premature Detonation

The detonation of a detonator or explosive prior to the intended time; usually accidental and dangerous

Pre-shear A form of overbreak control where the perimeter (outside) holes in the blast pattern are detonated before the other holes, also known as “pre-splitting”

Prill A cellular, spherical particle of AN; formed by spraying a concentrated AN solution against a stream of air

Primacord A heavy reinforced detonating cord

Primary Explosive

An explosive or explosive mixture that is sensitive to flame, friction, impact, and sparks; used in a detonator to initiate the base charge

Primer An explosive to which a detonator or other initiating device (detonating cord) has been attached; specifically, the cartridge or booster containing a detonator

Propagation Detonation of explosives by the shock wave from a nearby charge; also known as “sympathetic detonation”

PSI Pounds per square inch

Pull Wire Lighter

A flame-producing device used to ignite a safety fuse assembly; consisting of a hollow tube lined with an incendiary substance, and an external handle attached to a wire

Quantity Distance Table

A table listing the minimum distance quantities of an explosive may be kept or stored in relation to established areas or locations

Rated Capacity The maximum quantity of electric detonators that may be initiated by a blasting machine, as specified by the manufacturer; also refers to the GVW of a vehicle


RCmP Royal Canadian Mounted Police

RDx Research Development Explosive; Cyclotrimethylene-trinitramine; an explosive substance

Relay A common term for detonating connector

Remnant Any remaining portion of a blasted hole, including scar markings on the blasted material

Resistance The difficulty an electric current (ampere) has flowing through an electrical circuit; measured in ohms

RF Radio Frequency energy

Round A pattern that includes a cut; used to blast a face that is not “free” or open

Safety Fuse A core of special gunpowder tightly wrapped in a spirally formed cover of various textiles and waterproof materials; burns at approximately 130 seconds per metre (40 seconds per ft) at sea level; a component of a safety fuse assembly, and a reliable means of transporting a flame to ignite a detonator

Safety Fuse Assembly

A non-electric detonator attached to a length of safety fuse; may have an igniter cord connector attached to the other end of the fuse; also known as a “capped fuse” or “fuse-cap assembly”

Safety match A match that only ignites when struck against a specially prepared surface; may be used to ignite a single safety fuse assembly

Scaling The act of removing loose material; usually accomplished with machinery or a scaling bar

Scaling Bar A device used for scaling; a metal (steel or aluminum) bar having pointed and chisel ends

Scraper A non-sparking device for removing loose materials (rocks) from a bore hole prior to loading; commonly a 12 mm (1/2 in) copper rod with a dished end


Secondary Blasting

The use of explosives to reduce oversize material; includes mudcapping

Seismic Detonator

A high strength, instantaneous electric detonator used to initiate a seismic “in-hole” charge

Sequential Blasting

A method of firing holes in rotation (sequence) to reduce burden and provide many separate blasts; usually the holes with least resistance are blasted progressively; also known as “rotational firing”

Series Circuit A series of electric detonators with the leg wires connected so that the electrical current follows a single path through the entire blasting circuit

Series-in-Parallel Circuit

Two or more (balanced) series of electric detonators connected into a parallel blasting circuit

SFA Safety Fuse Assembly

Shaped Charge An explosive with a formed cavity specifically designed to produce a high velocity cutting or piercing jet of product reaction; usually lined with metal to create a jet of molten liner material

Shelf Life The recommended length of time that an explosive can be stored without losing its efficient performance characteristics

Shock Tube Hollow plastic tubing that transmits a shock wave

Shock Wave A pressure pulse that propagates at supersonic speeds

Shot See Blast

Shot Hole The remains of a blast hole after detonation; a seismic term used to describe a bore hole, a blast hole and/or a hole that was blasted

Shooter See Blaster


Shunt A metal (aluminum or brass) clip or foil used to short out an electric detonator by interconnecting the leg wires; also refers to the act of shorting out leg wires by twisting them together

Shuttlecock A plastic device to keep cartridges in a blast hole; resembles a shuttlecock used in badminton; also known as a “birdie”

Simplex Wire A single blasting wire usually contained in a protective plastic covering; distinct from duplex wire

Slider A common term for a sliding booster

Slip-on Booster A type of booster designed to slip on or over a detonator

Slurry An explosive consisting of oxidizing salts (AN, sodium nitrate, calcium nitrate), fuels (aluminum, oil), and sensitizers dispersed or dissolved in a water resistant gel; some slurries are cap-sensitive, while others are not and require a high strength primer in order to initiate; also known as “watergel”

Socket The remaining portion of a blast hole that did not break to its full depth; may contain some undetonated explosives; also referred to as “bootleg” or “butt”

SP Short Period; a type of delay in a detonator

Spacer A piece of material, usually clay or wood, placed between cartridges or charges in a blast hole; used to “string out” the explosives for better economy and reduce adverse effects (such as backbreak and fly material)

Spacing The distance between blast holes having approximately the same burden; usually refers to the average distance between holes in the same row

Spit The flame jet produced by a safety fuse at the moment of ignition; also refers to the flame jet that occurs at the notches of a spitter


Springing A blasting technique for opening up a pocket at the bottom of a blast hole; successive charges are loaded and blasted; used to remove stumps; also known as “bulled hole” or “stumping”

Static Electrical energy stored on a person or object; may discharge to a detonator and cause accidental detonation

Static Short The triangular compression in the leg wires of an electric detonator; located near the anti-static groove; serves to drain off static electricity

Stemming Inert material placed in the portion between the top of the explosive column and the collar of a blast hole; usually drill fines, pea gravel, or sand; intended to confine the explosive gases for an effective blast

Strength A measurement of the energy produced by a volume or unit weight of an explosive; used to express the capacity of an explosive to perform work

Subdrilling Drilling a bore hole below the desired elevation to ensure adequate breakage; also referred to as “subgrade”

Suitable Receptacle

An unlicenced, substantially constructed box or container with a lid secured by a lock; used for storage of no more than 100 detonators or 10 kilograms (22 lbs) of explosives (of which not more than 5 kg (11 lbs) may be a dynamite)

Tamp Compressing an explosive (cartridge), or stemming material, in a blast hole; usually with a tamping rod

Tamping Rod A non-sparking device for compressing an explosive or stemming material in a blast hole; usually made of wood or semi-conductive plastic; also known as a “loading stick”

Tester Common term for an instrument to measure resistance in an electrical blasting circuit; see Blasting Multimeter and Galvanometer


Thermalite A common brand of igniter cord

Throw The movement of muck during a blast; specifically the direction of movement; airborne muck is known as fly material

Tie-in A common term for “hook-up” or “wire up”

TNT Trinitrotoluene; a powerful, highly water-resistant explosive; a sensitizer for slurries and an ingredient in pentolite

Trim To remove (cut off) a section of detonating cord, safety fuse, or tubing

Toe The unbroken lower part of a face that has been blasted but did not break off or shear loose

Trunkline A length of detonating cord, or plastic tubing, used in a circuit to connect downlines (pig tails); may connect several branchlines

Tubing The hollow plastic pipe used in the shock tube initiation systems

ULC Underwriters Laboratories of Canada; a recognized standard for fire extinguishers; based on the ABC classification, with A for paper/wood fires, B for gas/oil, and C for electrical fires

V.O.D. Velocity of Detonation; the speed at which the detonation wave travels through a column of explosives.


Appendix 3: Simple Blast Design

There are sophisticated formulas and methods that can be used in blast design. These formulas use the variables of rock density, drill hole diameter, and explosives density to arrive at a drill pattern.

The drill pattern establishes the distribution of energy into the rock. The method outlined here offers a much simplified method of designing a bench blast.

One reliable formula for estimating blast design is based upon calculating the burden distance then proportioning other dimensions based upon the burden.

B =[(2 x SGe)]+ 1.5 De

SGr

Where: B = burden distance in feet SGe = specific gravity of the explosive column SGr = specific gravity of the rock De = explosive diameter in inches

This formula can be simplified to produce a RATIO of burden distance to hole diameter. The following table shows such a ratio.

Table 6: Ratio of Hole Diameter to Burden Distance

SpecificGravityofRock

SpecificGravityofExplosive

0.85 1.00 1.15 1.3 1.452.00 28 30 32 34 352.10 28 29 31 33 352.20 27 29 31 32 342.30 27 28 30 32 332.40 27 28 30 31 332.50 26 28 29 30 292.60 26 27 29 30 312.70 26 27 28 30 312.80 25 27 28 29 302.90 25 26 28 29 303.00 25 26 27 28 30


Table 7: Specific Gravity of Rocks

Basalt 2.8 – 3.0 Limestone 2.4 – 2.9Diabase 2.6 – 3.0 Marble 2.1 – 2.9Diorite 2.8 – 3.0 Micaschist 2.5 – 2.9Dolomite 2.8 – 2.9 Quartzite 2.0 – 2.8Gneiss 2.6 – 2.9 Sandstone 2.0 – 2.8Granite 2.6 – 2.9 Shale 2.4 – 2.8Hermatite 4.5 – 5.3 Slate 2.4 – 2.8

Basic Geometry of a Bench Blast

Burden distance

The burden distance is based upon the hole diameter, explosive diameter, the specific gravity of the rock, and the specific gravity of the explosive.

Stemming (T)

Stemming is required to confine the explosive gases, thus increasing rock movement and preventing flyrock. In a well-confined, well-designed blast, the stemming would be 0.7 times the burden distance (minimum requirements).

T = 0.7 x B

The stemming material is important to the blast design. Ideally, stemming material should be crushed rock with an average size of 1/20th of the drill hole diameter.

B=BurdenT=Stemming

J=SubdrillingL=LedgeHeight

H=HoleDepthS=Spacing


Subdrilling distance

Subdrilling is required to ensure the blast breaks to grade. In most cases, an adequate subdrilling distance can be approximated by

J = 0.3 x B (Range 0.2 - 0.5)

Hole-to-hole spacing

The spacing should be set at 1 - 2 times the burden.

Ratio of bench height to burden distance

For good fragmentation, minimal ground vibration, and limited flyrock, the ratio of burden to spacing should be ≥3.

Example calculation

A 6-metre high (19.6 ft) bench is to be drilled with 50 mm (2 inch) hole. The rock is granite, and the explosive to be used is dynamite with a density of 1.45. Calculate the layout dimensions.

From Table 7 of specific gravities, granite has a specific gravity of 2.7. Using Table 6, the intersection of 1.45 for dynamite and 2.7 for granite yields a ratio of hole diameter to burden distance of 31.

Thus the burden is set at:

B = 31 x 50 mm = 1550 mm (or 1.55 metres)

Stemming is set at:

T = 0.7 x 1.55 = 1.08 m

Subdrilling is set at:

J = 0.3 x 1.55 = 0.46 m

Spacing is set at:

S = 1.55 x 2 = 3.1 m


Example of Imperial calculations

Note that the ratio method is effective for metric or imperial measurements.

B = 31 x 2 inches = 62 inches = 5.17 feet T = 0.7 x 5.17 = 3.62 ft J = 0.3 x 5.17 = 1.55 ft S = 5.17 x 2 = 10.34 ft


Appendix 4: Electrical Calculations

Electric tables

The following condensed tables are provided to illustrate the procedures for calculating resistance.

Table 7: Resistance of Copper Blasting Wire

Gauge Ohmsper305Metres(1000ft)4 0.2486 0.3958 0.628

10 0.99912 1.58814 2.52516 4.01618 6.38520 10.15022 16.14023 20.360

Table 8: Resistance of Standard Electric Detonators

LengthoflegwireCopperWireOhms IronWireOhms

Metres Feet2 6.6 1.40 2.703 9.8 1.55 3.604 13.1 1.70 4.405 16.4 1.85 5.406 19.7 1.95 6.007 23.0 2.15 6.909 29.5 2.20 ----

12 39.4 2.25 ----15 49.2 2.35 ----20 65.6 2.80 ----25 82.0 3.20 ----30 98.4 3.35 ----

Note: Be sure to check the manufacturer’s specific resistances for the caps you are using.


These resistances represent nominal values from detonator resistance range specifications and apply only to standard electric detonators. Ensure that resistance tables used are correct for the detonators and wire being used.

Table 9: Resistance of Connecting Wire

Type Thickness Ohmsper305Metre(1000feet)

Copper 0.762 mm 0.030 in 11.50.724 mm 0.0285 in 12.70.533 mm 0.021 in 23.5

Iron 0.584 mm 0.023 in 124.0

Single series calculations

Example calculation #1

Situation: A blaster is required to blast a single series circuit containing two (2) standard electric detonators having 6 m (19.7 ft) copper leg wires and 305 m (1000 ft) of duplex 16 gauge lead wire.

Question: What is the total resistance of this circuit?

Resistance of one (1) electric detonator = 1.95 ohms

Resistance of two (2) detonators (2 x 1.95) = 3.90 ohms

Resistance of blasting line (1000 x 2 x 4.016) = 8.032 ohms 1000

Total resistance of the circuit (3.90 + 8.032) = 11.932 ohms

NOTE: It is permissible to “round off” the numbers to one decimal place; therefore the total calculated resistance of this circuit may be expressed as 11.9 ohms.



Situation: A blaster is required to blast a single series circuit containing thirty (30) standard electric detonators having 4 m (13.1 ft) iron leg wires and 229 m (750 ft) of duplex 12 gauge lead wire.



Resistance of thirty (30) detonators (30 x 4.40) = 132.00 ohms

Resistance of blasting line (750 x 2 x 1.588) = 2.38 ohms 1000

Total resistance of the circuit (132 + 2.38) = 134.38 ohms

NOTE: By “rounding off” the numbers to one decimal place, the calculated value of this circuit may be stated as 134.4 ohms.

Series-in-parallel calculations


Situation: A blaster is required to blast a series-in-parallel circuit containing, in two (2) series, a total of 20 standard electric detonators, each having 3 m (9.8 ft) copper leg wires and 76 m (250 ft) of duplex 14 gauge lead wire.



Resistance of one (1) series of 10 detonators = (10 x 1.55) = 15.50 ohms

Balance the circuit by placing 10 detonators in each series.

Resistance of two (2) series in parallel = (15.50/2) = 7.75 ohms

Divide the resistance of one (1) series by the number of series in the circuit.

Resistance of blasting wire = (250 x 2 x 2.525) = 1.26 ohms 1000

Total resistance of circuit (7.75 + 1.26) = 9.01 ohms



Situation: A blaster is required to blast a series-in-parallel circuit containing, in three (3) series, 75 electric detonators having 2 m (6.6 ft) iron leg wires and 457 m (1500 ft) of duplex 12 gauge copper lead wire.



Resistance of one (1) series of 25 detonators (25 x 2.70) = 67.50 ohms

Resistance of three (3) series-in-parallel (67.50 ÷ 3) = 22.50 ohms

Resistance of blasting wire (1500 x 2 x 1.588) = 4.76 ohms



Situation: A blaster is required to blast a series-in-parallel circuit containing, in four (4) series, a total of 200 detonators having 4 m (13.1 ft) copper leg wires, and 76 m (250 ft) of simplex 15 gauge copper connecting wire plus 305 m (1000 ft) of 8 gauge duplex copper firing cable.



Resistance of one (1) series of 50 detonators (50 x 1.70) = 85.00 ohms

Resistance of four (4) series-in-parallel (85.00/4) = 21.25 ohms

Resistance of lead wire (250 x 1 x 2.525) = 0.63 ohms 1000

Resistance of firing cable (1000 x 2 x .628) = 1.256 ohms 1000

Total resistance of circuit (21.25 + 0.63 + 1.256) = 23.14 ohms


Power line blasting calculations

Example calculation #1: single series blast

Both amperage and voltage calculations are required for power line blasting.

Situation: A blaster is required to blast, in a single series, 50 standard electric detonators having 6 m (19.7 ft) copper leg wires. The blasting wire is 153 m (500 ft) of duplex 14 gauge copper lead wire.

Questions: 1. What is the total resistance of this circuit? 2. How much current (amperage) is required? 3. How much voltage is required?

Resistance of one (1) electric detonator = 1.95 ohms (see Table 8)

Resistance of 50 detonators (50 x 1.95) = 97.50 ohms

Resistance of blasting wire (500 x 2 x 2.525) = 2.525 ohms 1000 (see Table 9)


Total current required for one (1) series (1 x 1.5) = 1.5 amps

Total voltage required for circuit V = I x R = 1.5 x 100.025 = 150.0375 volts

Note: a power source producing in excess of 150 volts and 1.5 amps is required to fire this circuit.


Example calculation #2: series-in parallel blast

Situation: A blaster is required to blast in four (4) series, 160 standard electric detonators having 2 m (6.6 ft) copper leg wires. The blasting wire is 153 m (500 ft) of simplex 16 gauge copper connecting wire plus 305 m (1000 ft) of duplex 12 gauge copper firing cable.

Questions: 1. What is the total resistance of this circuit? 2. How much current (amperage) is required? 3. How much voltage is required?


Resistance of each series of 40 detonators (40 x 1.40) = 56.00 ohms

Resistance of four (4) series-in-parallel (56.0/4) = 14.00 ohms

Resistance of lead wire (500 x 1 x 4.016) = 2.01 ohms 1000

Resistance of firing cable (1000 x 2 x 1.588) = 3.18 ohms 1000

Total resistance of circuit (14.00 + 2.01 + 3.18) = 19.19 ohms

Total amperage required for four (4) series (4 x 1.5) = 6.0 amps

Total voltage required for the circuit V = I x R 6.0 x 19.19 = 115.14 volts

NOTE: a power source producing in excess of 115.1 volts and 6 amps is required to fire this circuit.


Appendix 5: Obsolescent or Limited-Use Explosive Systems

Low energy detonating cord systems

Before the advent of the shock tube system in the early 1970s, a number of low energy detonating cord systems were used with ANFO and other non-cap-sensitive explosives to bottom initiate blast holes without side-initiating the explosive column.

These detonating cords were very low energy, usually containing 1 kg of explosive per 1000 metres of cord. (Typically, most detonating cords have an explosive load of between 5 and 22 kg of PETN per 1000 metres.)

These cords have been marketed under various trade names. “Anoline” and “Cordline” have been used in British Columbia, and their characteristics are as follows:

Units are factory-assembled with detonator, pre-defined length of cord, and quick-connectAvailable in standard and “reinforced” configuration for higher tensile strengthAvailable with downline high-strength detonators of various delaysSupplied with a quick-connect plastic fitting for attaching to detonating cord trunkline

Gas-initiated system

These systems use what is best described as a “piping” layout consisting of small diameter plastic tubing and plastic fittings. A downhole delay detonator is used. The system is connected in a series using the tubing, fittings, and detonator.

When the system is connected, it is filled with inert gas and tested for continuity. Once the system is tested, it is prepared for firing by charging the system with a combustible gas. At any time before firing, the system can be purged and re-filled with inert gas thus rendering it “safe.”

The advantages of the system are:Except for the downhole detonators, the system is safe until it is charged for firingThe system can be tested prior to firingIt can be “dis-armed” if required

This system has been marketed under the names “Hercudet” and “Iredet.” The system has mostly been replaced by shock tube systems but still may be in use in large open pit mines.

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Magnadet

The “Magnadet” system is an electrical initiation method employing features that are highly resistant to electrical hazards. It consists of a high-strength detonator with attached closed-circuit leg wires and connector. The detonator unit remains a closed-circuit and is thus highly resistant to:

Static electricityGalvanic actionRadio frequenciesStray currentsInduction

The detonators are connected to a firing line that produces an alternating current at a frequency of 15,000 Hz or more. The connector works as a miniature transformer that converts the firing pulse into a current that fires the detonator. Because of the uniqueness of the firing pulse and the “tuned” nature of the connector transformer and circuit, the system is highly resistant to all electric sources except the firing source.

The pulse of energy is unique; thus, the system is highly resistant.

Exploding bridgewire system

The EBW detonator is a special type of initiating device, less sensitive than conventional detonators as it does not contain a primer charge. When a high energy electrical pulse from a firing system is applied to the gold bridgewire, it explodes and initiates the base charge of high explosive.

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FiringModule

SeismicRecorderorother

ElectricalRecordingor

TriggeringDevice

FiringSystemControlUnit

CoatedMulti-ConductorHook-UpWirewithShield EBWDetonatorTaped

toMainBlastingChargeorDetonatingCord

Upto30m(100 ´ )ofTwinLeadHook-UpWire

Its unique construction contributes to its safety features. The manufacturer states an EBW detonator will not detonate when exposed to:

Electro-static dischargesRadio frequency energyStray currentLow voltage currentHigh temperatures

EBW Deployment Method

There are several models of EBW firing systems. All feature a control unit and a firing module. This permits remote arming and firing, keeping the operator well away from the high voltage.

The FS-9 Firing System comprises two parts: the control unit and the firing module.

Control unitThe control unit is a sealed metal case containing rechargeable nickel cadmium batteries, energized by an internal charger connected to a standard 110 volt AC, 60 cycle outlet. A test lamp indicates when the batteries are adequately charged.

The control unit has a safeguard in the form of a “shorting plug.” Until this plug is mated to the “Safety Interlock” connection, it is impossible to arm the firing module.

Unless the firing is aborted, the output voltage will arm the firing module and initiate the blasting circuit within a few seconds. To abort the firing, release one or both of the “Hold-to-Arm” and “Hold-to-Fire” switches.

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Firing moduleThe firing module is a sealed metal box housing a voltage conversion system that increases the input voltage of between 32 and 40 volts to approximately 3,000 volts. When this level is reached, an automatic trigger system discharges the energy into the blasting circuit.

Blasting wireBlasting wire for an EBW circuit consists of hook-up wire and lead wire:

Hook-up wire used between the control unit and the firing module is duplex (twin conductor) copper wire. Each wire is insulated and must be 20 gauge or larger.Lead wire used between the firing module and an EBW detonator is duplex insulated copper wire 20 gauge or larger. It must not exceed 30 m (100 ft) or be less than 3 m (10 ft) in length. The twin wires must be molded together to maintain minimum current inductance.

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Appendix 6: Seismic Blasting

In seismic blasting, the explosive charge set in the ground produces a shock wave that travels through the surrounding strata to the surface. Sensitive electronic instruments record the shock waves in order to ascertain the geological formation of the area.

Components

Electric detonators used for “in-hole” seismic blasting are instantaneous, with no delay element and no significant time lag between the bridge wire breaking and detonation. This is essential for accurate seismic recordings.

Seismic electric detonators should have:The ability to undergo extreme temperature changes without loss of performanceGood static resistanceAn anti-static grooveAn insulating shunt at the ends of the leg wiresGood resistance against high water pressure (hydrostatic heads)Aluminum alloy shells to resist corrosionFlexible leg wire insulation even in cold temperatures (plastic)No significant time lag between the bridge wire breaking and detonationHigh strength for reliable initiation of the charge

Seismic electric detonators have aluminum alloy shells approximately 7 mm (3/8 in) diameter and 50 mm (2 in) long. A heat sensitive primary charge (lead styphnate), and high explosive (pentaerythritol tetranitrate) PETN is pressed into the base end. All are “high strength” to cope with external water pressures (hydrostatic heads) often encountered in loaded holes.

Two insulated leg wires enter the shell through a rubber plug that holds them in position and forms a water-resistant seal. The leg wires connect to a “bridgewire” embedded in the primary charge. When an electric current is passed through the filament, it becomes hot, igniting the primary charge, which detonates the base charge of PETN.

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Leg wires

Seismic detonator leg wires are made of copper coated with a thin layer of tin and covered with plastic insulation, which is flexible and resistant to abrasion. Most have 20 gauge leg wires and come in various lengths ranging from 1 metre (3.3 ft) to 45 m (150 ft); leg wires as long as 122 m (400 ft) are available. The leg wires distinguish seismic detonators from other electric detonators. They are usually longer and each has a distinct colour. Seismic detonators are electrically incompatible with other electric detonators and must not be connected in the same circuit. Seismic detonators from different manufacturers should never be used in the same circuit.

Blasting machine

Condenser discharge blasting machines are commonly used in seismic work. They employ capacitors to “step up” the voltage to the required level before discharging it into the circuit. Seismic recording equipment often has a built-in blasting machine with special devices to test the circuit, discharge, and limit the time of current application.

After connecting the blasting circuit to the equipment, the blaster tests for circuit continuity with the built-in galvanometer. Then, after checking that final precautions have been taken, the blaster will discharge the blasting machine by means of a radio-tone.

It is critical that the blaster understands and adheres to the manufacturer’s instructions for maintaining and testing a blasting machine. In extremely cold temperatures, many blasting machines may malfunction. Unless specifically designed to operate in cold temperatures, the machine should be kept warm at all times.

When charging the machine, continue pressing the charge button after the ready light shines until the whine produced reaches a steady note. In cold temperatures, the “last little bit” of voltage may be necessary to properly fire the circuit.

Resistance calculations

The resistance of each seismic detonator, each series of detonators, and the complete circuit must be determined.


Testing the circuit

Tests of seismic detonators, series of detonators, or the complete circuit are to be done using a testing device acceptable to WorkSafeBC. These include a blasting galvanometer and blasting multimeter. In this manual, the use of the term “galvanometer” includes any acceptable testing device.

Unless a downline of detonating cord is used to initiate an “in-hole” seismic charge, every seismic detonator must be tested for continuity immediately after it is placed in the hole. Stemming material must not to be placed in a loaded hole until the circuit continuity of at least one (1) seismic detonator is verified and recorded in the blasting log.

After stemming material is placed in a loaded hole, it may be extremely difficult or impossible to detonate the charge should there be a fault in the circuit. A downline of detonating cord will allow the charge to be primed and fired from the surface. Most seismic operations do not use detonating cord because it can interfere with seismic readings.

Whether or not detonating cord is used, each series of seismic detonators and the complete circuit must be tested. An electrical blast must not be fired unless the test reading agrees with the calculated resistance for that series and the complete circuit.

When all the seismic detonators have been connected into a series, it should be tested before being connected to the firing cable, and the firing cable should be tested separately before the circuit is completed.

Procedure

Testing procedures (single series) are explained in Chapter 22.

Firing calculations

In addition to resistance calculations, any candidate who wishes to qualify as a “shooter” must be capable of doing firing calculations to determine amperage and voltage requirements.

Amperage

A seismic electric detonator requires a certain minimum amperage for proper initiation. Ohm’s Law and power calculations are explained in Chapter 22.


Firing current

Although “Ohm’s Law” calculations cover the basic principles, consideration must also be given to the duration of the firing current.

The manufacturer will state the recommended firing current for each seismic detonator in amperes of direct current (DC). It is assumed the current will be applied for the length of time necessary to initiate all detonators in the circuit, usually 1 ms (0.001 sec).

The output current from a conventional blasting machine tends to decrease over time. It is therefore incapable of maintaining a constant (steady) firing current for the necessary time period. It is important to determine the amount of electrical energy that can be delivered by a blasting machine to the circuit over a time span of 1 ms.

Before using a blasting machine to fire a circuit containing seismic detonators, ascertain its firing capacity. This capacity, calculated by the manufacturer, manufacturer’s representative, or another qualified person, must be affixed to the blasting machine.

Safety precautions

Safety precautions should be taken when using electric detonators for seismic blasting.

Keep the leg wires short-circuited until they are wired in to the circuit. The “shunt” may be removed temporarily to test the detonator.Keep explosives and detonators in separate containers, or a safe distance apart, until the hole has been drilled.Do not assemble a primer (charge) until the hole is ready for loading.Discontinue operations during dust, snow, or electrical storms. Static build-up can go unnoticed.Do not wear clothing made of synthetic materials in proximity to, or while handling, a seismic detonator.In cold temperatures, avoid excessive friction and contact with synthetic material such as plastic. When possible, ground yourself to discharge static.Do not throw detonator leg wires through the air or drag them along the ground.Do not drop explosives into a hole.

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Do not lower a charge into a hole by means of the detonator leg wires. Use a loading pole, lowering hook, or other device acceptable to WorkSafeBC.Do not allow the leg wires to slide through your hand. Lower the charge slowly into the hole.Avoid “in-hole” connections to leg wires. If unavoidable, make sure the connection is secure and insulated with tape or other effective means. Splices should be staggered (at separate locations) to avoid short-circuiting.Where leg wires could suffer damage from severe field conditions:

Prime the charge with at least 2 detonators, orUse a downline of detonating cord to fire the charge

If a primed charge is damaged and cannot be detonated, place an additional primed charge in the hole to detonate the original charge.Do not place stemming material in a loaded hole until the circuit continuity of at least one (1) detonator is verified and recorded in the blasting log. This does not apply if detonating cord is used to initiate the charge.Do not leave a loaded hole unguarded unless:

The hole is in an isolated areaThe leg wires are shunted and suitably coveredThe location of the hole is recorded in the blasting log

Do not leave a seismic charge in a hole beyond the period recommended by the manufacturer. In no instance is this to exceed 30 days.Do not mix one brand of seismic detonator with another brand, or any other type of electric detonator.Use an appropriate blasting machine, in accordance with the manufacturer’s specifications.

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