Wood Dust Explosion Prevention - Manitoba · •Explosion pressure and flame will propagate through process interconnections to other plant equipment or personnel occupied areas

Wood Dust Explosion Wood Dust Explosion

Prevention Prevention

John E. John E. BachynskiBachynski B.Sc., B.Sc., P.EngP.Eng..

PresidentPresident

EPM Consulting Ltd.EPM Consulting Ltd.

Brief History of Major Events

The top 100’ of head house atop this 250’ tall grain elevator facility was blown

away, killing 36 and injuring 9, making it the worst such disaster in U.S. history.

Silo holding 300 tons of Ammonium Nitrate. 29 killed, 441 hospitalized. 3000 homes and apartments damaged or destroyed.

CTA Acoustics, Corbin KY,

February 2003

Resin dust, 7 fatalities, 37 injuries

Tafisa Canada

Particle Board Facility. No injuries. Destroyed plant.

Imperial Sugar Port Wentworth, Ga

February 7, 2008

14 killed, 40+injured. An over heated bearing caused an primary explosion resulting in multiple secondary explosions.

Burns Lake, British Columbia

January 20, 2012

2 killed, 20+injured.

Lakeland Sawmill, Prince George

April 23, 2012

2 killed, 24 injured.

West Fertilizer Company West,

Texas April 2013

15 killed, 160 injured. Plant was leveled along with a near by

assisted living apartment building.

Flour Mill Statesville, N.C

April 2013

1 seriously injured

GM Plant Kunshan, China

August 2014

75 killed, 200+injured.

Fine airborne metal dust from polishing hub caps ignited

Almost 125 dust explosions / year Almost 125 dust explosions / year or or

about ONE every THREE DAYSabout ONE every THREE DAYS

Fatality in Operations

• Worker in a boom lift changing a light bulb

• Multiple events creating sequential suspended dust clouds and explosions

• 3rd degree burns >70% of his body resulting in fatality

38%

15% 12%

9%

7%

7%

6%

4% 3%

Wood Products

Food Products

Primary Metal Ind

Chemical Mfg

Pulp/Paper

Mineral

Plastic/ Rubber

Utility

Other

FM Global property loss prevention data

2007

42%

15%

10% 9%

8%

8%

5%

3%

Wood

Food

Chemical

Metal

Coal

Plastic/Rubber/Resin

Paper

Various


2007

40%

13%

5%

5% 3% 3% 3%

28%

Dust Collector

Impact Equipment

Storage Silo

Processing Equipment

Oven

Conveyor

Grain Elevator

Other


2007

These numbers EXCLUDE gas and mining incidents

Sample MEC DataSample MEC Data

Dust Dust Concentration Concentration

[g/m[g/m33]]

PPmm [bar(g)][bar(g)]

(dP/dt)(dP/dt)mm [bar/s][bar/s]

7070 5050 4040 4040 3030 2020 2020

3.83.8 2.92.9 1.71.7 0.80.8 1.61.6 0.20.2 0.20.2

163163 107107 3434 66 3838 22 11

Most dust explosions occur inside process

equipment. (Optically thick dust clouds in the

flammable range.)

But not always! Primary and secondary explosions!

Explosive RangeExplosive Range

Ignition Source

Fuel

Oxidant

Mixing Confinement

Ignition Source

Fuel

Oxidant

Mixing Confinement

Fuel

Oxidant

Ignition Source

Ignition Source Ignition Source ControlControl

Dust Accumulation Dust Accumulation (Fuel) Management(Fuel) Management

For static electricity to be a hazard, four conditions must be met:

• Energy storage capacity in an ungrounded human body: 40-60mj

Vs.

General Guidelines Where

Dust AccumulationsDust Accumulations

Can you tell the Can you tell the color of this plate?color of this plate?

Hazardous Dust Accumulation Examples



Holes in Equipment

Holes in Equipment










5 – Dust Collection Systems and Associated Risks

40%

13%

5%

5% 3% 3% 3%

28%

Dust Collector

Impact Equipment

Storage Silo

Processing Equipment

Oven

Conveyor

Grain Elevator

Other


2007

Dust Collector

Dust Collector

Vibrating Bag Hangers

Fabric Bags

Dust

Dusty

Air

Clean

Air Dusty

Air

Clean

Air

Fabric Bags

Dust

•• Explosion pressure and flame Explosion pressure and flame willwill propagate propagate through process interconnections to other plant through process interconnections to other plant equipment or personnel occupied areas. equipment or personnel occupied areas.

•• Explosions in connected vessels or dust Explosions in connected vessels or dust containing areas containing areas (secondary explosions)(secondary explosions) tend tend to be of higher severity than explosions occurring to be of higher severity than explosions occurring in single unconnected vessels because of prein single unconnected vessels because of pre--compression, flamecompression, flame--jet ignition, and dust layer jet ignition, and dust layer disbursement. disbursement.

•• StSt--2 & 3 deflagrations 2 & 3 deflagrations can accelerate to can accelerate to detonation velocitiesdetonation velocities while traveling through while traveling through pipelinespipelines..

Successful Successful Explosion Explosion

VentingVenting Explosion Explosion Propagation Propagation

Through Inlet Through Inlet DuctDuct

Explosion Isolation

Inlet Explosion Isolation(sInlet Explosion Isolation(s))

NEW

NEW

NEW

1. New as of 2014 Publication

Pre-2014 NFPA 69

2014 NFPA 69

Abort GateAbort Gate



1212


4000 fpm4000 fpm

13 Ft.13 Ft.

66 fps66 fps

Reaction time = 200 millisecondsReaction time = 200 milliseconds

Abort Gate Detection Abort Gate Detection

ExampleExample

4000 fpm4000 fpm

13 Ft.13 Ft.

66 fps66 fps



ExampleExample

Proper Duct Velocity For DesignProper Duct Velocity For Design

13 Ft.13 Ft.



ExampleExample

5000 fpm5000 fpm

83 fps83 fps

13 Ft.13 Ft.



ExampleExample

5000 fpm5000 fpm

83 fps83 fps

Duct Velocity Too HighDuct Velocity Too High

Wood Processing Dust Collection System Example

Storage

Basement

Process Floor

Storage

Basement

Process Floor

Storage

Basement

Process Floor

Storage

Basement

Process Floor

Storage

Basement

Process Floor

Storage

Basement

Process Floor

Explosion Vent

Typical Planer Mill Plan

Typical Sawmill Plan

Typical Debarker Building

Importance of Enclosures & Containment Importance of Enclosures & Containment

ACGIH Industrial Ventilation Example

ACGIH Industrial Ventilation Example

Material TypeMaterial Type ExamplesExamples Transport VelocityTransport Velocity

Vapors, gases, smokeVapors, gases, smoke All vapors, gases and smokeAll vapors, gases and smoke 10001000--2000 fpm2000 fpm

FumesFumes WeldingWelding 20002000--2500 fpm2500 fpm

Very Fine Light DustVery Fine Light Dust Wood flour cotton lintWood flour cotton lint 25002500--3000 fpm3000 fpm

Dry Dusts & PowdersDry Dusts & Powders Fine rubber dust, cotton dustFine rubber dust, cotton dust 30003000--4000 fpm4000 fpm

Average Industrial DustAverage Industrial Dust Grinding dust, coffee beans, Grinding dust, coffee beans, silica flour, general material silica flour, general material handlinghandling

35003500--4000 fpm4000 fpm

Heavy DustsHeavy Dusts Sawdust (heavy & wet), metal Sawdust (heavy & wet), metal turnings, wood blocksturnings, wood blocks

40004000--4500 fpm4500 fpm

12”Ø

12”Ø 9”Ø

3500 FPM 2700 CFM

2700 CFM 6300 FPM

ΔP=1.3” WG per 100ft

ΔP= 5.5” WG per 100ft 5.5”

Dust Collector Differential Pressure

6”Ø

18”Ø 16”Ø 14”Ø 11”Ø

20”Ø

System Velocity

= 4000 fpm

6”Ø

18”Ø 16”Ø 14”Ø 11”Ø

20”Ø

System Velocity

= 4000 fpm

Condensation in

ducting, driving up

Static Line Pressure

Higher Static

Pressure Than

With Dry Ducting

Pressure Up

24” w.g.

6”Ø

18”Ø 16”Ø 14”Ø 11”Ø

Dirty Dust

Collector Bags

Higher Static

Pressure Than

With A Clean

Dust Collector

20”Ø

System Velocity

= 4000 fpm

Pressure Up

6” w.g.

6”Ø

Very High

Hood Loss

20”Ø

Higher Static

Pressure Than

The Longest Run

1000

System Velocity

= 4000 fpm

Pressure Up

9” w.g.

4”Ø

20”Ø

Very High Velocity

Pressure (Long, Thin Run)

Higher Static

Pressure Than

The Longest Run

System Velocity

= 4000 fpm

Pressure Up

26” w.g.

Dust Explosion

Prevention

Contributing Factors

HSEHSE ASHRAEASHRAE OSHAOSHA CSBCSB NFPANFPA IEEEIEEE INSURANCEINSURANCE FABFAB--CONTRACTORSCONTRACTORS JOHSJOHS COSTCOST FIRE MARSHALLFIRE MARSHALL AIHAAIHA DEPT OF ENVIRONMENTDEPT OF ENVIRONMENT DOWNTIMEDOWNTIME COMBUSTIBLE DUST POLICY COMBUSTIBLE DUST POLICY

INSTITUTEINSTITUTE DSEARDSEAR EHSREHSR

FCCFCC WSBCWSBC

CSACSA DEPT OF LABOURDEPT OF LABOUR

LEGALLEGAL EQUIPMENT EQUIPMENT SUPPLIERSSUPPLIERS

ENGINEERINGENGINEERING WHIMSWHIMS

OPERATIONSOPERATIONS NECNEC

MSDSMSDS MAINTENANCEMAINTENANCE

SMACNASMACNA DEV. CONTROLDEV. CONTROL

ATEXATEX CORPORATE POLICYCORPORATE POLICY

ACGIHACGIH NEPNEP

AIChEAIChE

CANADA ELECTRICAL

CODE

CANADA ELECTRICAL

CODE

NFPA 68

NFPA 69

NFPA 77

NFPA 91

NFPA 654

NFPA 664

NFPA 68

NFPA 69

NFPA 77

NFPA 91

NFPA 654

NFPA 664 NFPA 70 (NEC) NFPA 70 (NEC)

NFPA 499 NFPA 499

CANADA BUILDING

CODE

CANADA BUILDING

CODE

FIRE CODE OF CANADA

FIRE CODE OF CANADA

BC FIRE CODE BC FIRE CODE

WORKSAFE BC

WORKSAFE BC

INSURERS INSURERS

• NFPA-61 2013

• NFPA-68 2013

• NFPA-69 2014

• NFPA-70 2014

• NFPA-77 2014

• NFPA-91 2010

Documents

Wood Dust Explosion Prevention - Manitoba · •Explosion pressure and flame will propagate through process interconnections to other plant equipment or personnel occupied areas