Storage and Classification Chemicals

7/30/2019 Storage and Classification Chemicals

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CLASSIFICATION OF HAZARDOUS SUBSTANCES

The hazardous substances are classified into eight classes. These are as under :

CLASS 1 EXPLOSIVESCLASS 2 GASES, COMPRESSED, LIQUEFIED, DISSOLVED OR DEEPLY

REFRIGERATED, INFLAMMABLE GASES, POISON (TOXIC) GASES.

CLASS 3 INFLAMMABLE LIQUIDSCLASS 4 INFLAMMABL SOLIDS, SUBSTANCES LIABLE TO SPONTANEOUSCONBUSTION; SUBSTANCES WHICH ON CONTACT WITH WATEREMIT INFLAMMABLE GASES.Division 4.1 Inflammable solids

. .

Division 4.3 Substances, which in contact with water, emitinflammable gases.

CLASS 5 OXIDISING SUBSTANCESDivision 5.1 oxidizing substancesDivision 5.2 Organic peroxides

CLASS 6 POISONOUS (TOXIC) AND INFECTIOUS SUBSTANCESDivision 6.1 Poisonous (toxic) substancesDivision 6.2 Infectious substances

CLASS 7 RADIOACTIVE SUBSTANCESCLASS 8 CORROSIVES

For details, the Central Motor Vehicles Rules may be referred.


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HAZCHEM CODIFICATIONHAZCHEM Code is based on pictorial representations consist of a

diamond, as shown in the figure, divided into 4 parts. These

parts, starting from left block (in clockwise direction), represent

Health Hazard, Flammability Hazard, Reactivity Hazard and

Space for additional information such as water reactivity,

oxidant and radiation hazard. The colour codes for these

hazards are : blue for health, red for flammability, yellow forreactivity and colourless for additional information. The

intensity of hazard is grouped into five classes with numerical

indications as 0, 1, 2, 3 & 4 in the ascending order of hazard

intensity. In the following lines, these hazard intensities areexplained, with the numeral on the left indicating the hazard

intensity.


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HAZCHEM CODE

Flammability(Red)

Health(Blue)

Reactivity(YellowYellow)

WOXY

W : Indicates possible hazard inuse of water.

OXY: Indicates oxidizing chemicals.


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At a minimum, chemicals should be segregated as:At a minimum, chemicals should be segregated as:Chemical StorageChemical Storage Hazard ClassHazard Class

CorrosivesCorrosives

5

Flammable LiquidsFlammable Liquids

Poisons or Toxic ChemicalsPoisons or Toxic Chemicals

Reactive (water or time sensitive)Reactive (water or time sensitive)


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NFPA-National Fire

Protection Association

HMIS-Hazardous Materials

Identification System


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FIREFIRE

FIRE IS A RAPID, SELF-SUSTAINED OXIDATION PROCESS ACCOMPANIED BY THE

RELEASE OF ENERGY IN THE FORM OF HEAT AND LIGHT OF VARYING INTENSITY.

FIRE RESULTS FROM THE COMBINATION OF FUEL, HEAT AND OXYGEN. WHEN A

SUBSTANCE IS HEATED TO A CERTAIN TEMPERATURE CALLED THE IGNITION

TEMPERATURE THE MATERIAL WILL IGNITE AND CONTINUE TO BURN AS LONG AS

THERE IS FUEL, THE PROPER TEMPERATURE AND A SUPPLY OF OXYGEN (AIR).


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FIRE TRIANGLEFIRE TRIANGLE

HEATOXYGEN

THREE ELEMENTS ARE NECESSARY FOR INITIATION OF FIRE:

1. FUEL IN THE FORM OF VAPOUR, LIQUID OR SOLID.

2. A SOURCE OF IGNITION SUFFICIENT TO INITIATE & PROPAGATE THE FIRE.

3. OXYGEN IN SUFFICIENT PROPORTION TO FORM A COMBUSTIBLE MIXTURE.


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METHODS OF EXTINGUISHMENTS OF FIREMETHODS OF EXTINGUISHMENTS OF FIRE

1. STARVATION : ELIMINATION OF FUEL

2. SMOTHERING : LIMITING OF OXYGEN

3. COOLING : LIMITING TEMPERATURE

STARVATION : STARVATION IS ACCOMPLISHED BY REMOVING COMBUSTIBLES FROM

THE NEIGHBOURHOOD OF THE FIRE OR BY REMOVING FIRE FORM THE MASS OF

COMBUSTIBLE MATERIALS. IT IS ALSO ACHIEVED BY SUBDIVIDING BURNING

MATERIALS TO SMALL ISOLATED POCKETS OF FIRE.

SMOTHERING : SMOTHERING IS ACCOMPLISHED BY ELIMINATING OR DILUTING THE

AVAILABLE OXYGEN WITH INERT GAS OR COVERING THE FUEL SURFACE BY A

SMOTHERING AGENT LIKE FOAM.

COOLING : IF THE RATE AT WHICH HEAT IS GENERATED BY COMBUSTION IS LESS

THAN THE RATE AT WHICH IT IS GETTING DISSIPATED THEN THE COMBUSTION

CANNOT PERSIST. APPLICATION OF WATER JET OR SPRAY TO A FIRE RESULTS IN ITS

EXTINGUISHMENTS BY THIS FUNDAMENTAL PRINCIPLE.


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CLASSIFICATION OF FIRECLASSIFICATION OF FIRE

INDIAN STANDARDS IS:2190 CLASSIFIES THE FIRE IN FOUR CATEGORIES

ACCORDING TO THE TYPE OF MATERIAL BURNING.

CLASS A ; FIRES INVOLVING ORDINARY COMBUSTIBLE MATERIAL LIKE WOOD, PAPER,

TEXTILES ETC. WHERE THE COOLING EFFECT OF WATER IS ESSENTIAL FOR

EXTINGUISHMENTS OF FIRE.

EXTINGUISHING MEDIA-WATER

CLASS B : FIRES IN FLAMMABLE LIQUIDS LIKE OILS, SOLVENTS, PETROLEUM

, .

EXTINGUISH THE FIRE.

EXTINGUISHING MEDIA-FOAM, CARBON DIOXIDE, DRY CHEMICAL POWDER.

CLASS C: FIRES INVOLVING GASES OR LIQUEFIED GASES IN THE FORM OF A LIQUID

SPILLAGE, OR A LIQUID OR GAS LEAK. HERE IT IS NECESSARY TO DILUTE THE

BURNING GAS AT A VERY FAST RATE WITH AN INERT GAS OR POWDER.

EXTINGUISHING MEDIA - CARBON DIOXIDE, DRY CHEMICAL POWDER. THE BEST

WAY TO EXTINGUISH SUCH FIRES IS BY STOPPING THE FLOW OF FUEL GAS TO FIRE.CONTAINER IS KEPT COOL WITH WATER SPRAY.


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CLASSIFICATION OF FIRECLASSIFICATION OF FIRE

CLASS D : FIRES INVOLVING METALS LIKE MAGNESIUM, ALUMINUM, ZINC,POTASSIUM ETC. WHERE THE BURNING METAL IS REACTIVE TO WATER AND WHICH

REQUIRE SPECIAL EXTINGUISHING MEDIA.

EXTINGUISHING MEDIA- SPECIAL DRY POWDER.

ELECTRICAL FIRE : ELECTRICAL FIRES ARE NOT TREATED AS A CLASS OF THEIR

OWN, SINCE ANY FIRE INVOLVING, OR STARTED BY, ELECTRICAL EQUIPMENT MUST,

IN FACT, FALL INTO ONE OF THE OTHER CATEGORIES.

THE NORMAL PROCEDURE FOR DEALING WITH AN ELECTRICAL FIRE IS TO CUT OFF

ELECTRICITY AND USE AN EXTINGUISHING MEDIA APPROPRIATE TO WHAT IS

BURNING.


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WATERWATERThe water is the best extinguishing media for Class A

Fires. It is -

Readily available. Have good absorbing capacity. can be used as cooling agent, fire fighting, producing

foam etc., ,

emulsification [only in case of heavy oils], dilution.

LimitationsLimitations:: On1. Energized equipments and

2. Water reactive metals.


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FOAMFOAMIt is considered to be the best extinguishing medium forClass B fires.

The foam is the mass of air bubbles formed by aerationof foam solution made up of the water and foamconcentrate.

The foam extinguishes the fire of liquid hydrocarbonsInsulating the surface of fuel.Prevent release ofvapours. Prevent mixing of vapour and atmospheric

oxygen forming a blanket. The foam is classified in two types depending on the

method of generation

i.e. chemical and mechanical foam


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Chemical foamChemical foamAs the name suggests it is formed by the chemicalreaction between the two chemicals namely Sodium

bicarbonate and Aluminums Sulphide. The use isrestricted to the portable extinguishers and nowthey are considered as obsolete.

6 NaHCO3 + Al(SO4)3 = 3Na2SO4 + 2Al(OH)3 + 6CO2

Aluminum hydroxide decomposes at about 180 C by

absorbing considerable amount of heat in theprocess and giving off water vapor.


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Mechanical foam

This foam is formed by mechanical agitation of thefoam solution. There are various types such asprotein foam, aqueous film forming foam, film formingfluoroprotein, alcohol resistant foam etc. used forfire fighting.

Method of application of foam -- Foam should notbe directly applied on the surface of the burningliquid whereas it should be applied in such manner so

that it will slide down and spread on the surface ofthe burning liquid.


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DRY CHEMICAL POWDERDRY CHEMICAL POWDER

The dry chemical powder is used to extinguish the Class B andClass C fires. The DCP for Class A fires is also available andfor Class D fires special dry chemical is used.

The most commonly used DCP are: 1. Sodium Bicarbonate. 2. Potassium Bicarbonate. 3. Monoammonium Phosphate. It also called as ABC

, , . 4. Monnex.: Urea based powder have decrepitating

property to shatter into small particles of sub- micronsize on approaching flame front. It is 6 timeseffective than ordinary DCP.

5. Ternary Eutectic Chloride : TEC powder is used to

extinguish the combustible metal fires. The powdermelts and forms the crust over the metal surfacethereby extinguishing the fires. It is composed of threechlorides namely Sodium , Potassium and BariumChloride.


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EXTINGUISHMENT MECHANISM OF DCPEXTINGUISHMENT MECHANISM OF DCP

Sodium Bicarbonate: When DCP enters the combustion zone,it decomposes by the heat of the flame to liberate water,water vapours and carbon dioxide.

2 NaHCO3 ------- Na2CO3 + H2O + CO2 The sodium Carbonate further decomposes to give

Na2CO3 -------- Na2O + CONa2O --------- 2NaOH

Sodium Hydroxide produced during last step reacts with H & OHradicals which are active in fire to give water vapours.NaOH + H ------- Na + H2ONaOH + OH ----- NaO + H2O

AlsoNaO + H ------- NaOHNa + OH ------- NaOH

This way all the H and OH radicals in fire are removed by breakingthe chain reaction and thus extinguish the fire.


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CLASS

OF

FIRE

DESCRIPTION EXTINGUISHING MEDIUM INDIAN

STANDARD

A Fire involving ordinary combustible

materials like wood, paper, textiles, etc.

Where the cooling effect of water is

essential for the extinction of fires

Water 934-1976

940-1976

6234-1971

B Fire inflammable liquids like oils,

solvents, petroleum products, varnishes,

paints etc. where a blanketing effect is

essential

Foam ** carbon dioxide dry

chemical powder. Not

suitable for alcohol and

other water miscible

flammable liquids

933-1976

2878-1976

2171-1976

(4308)-1982

C Fires involving gaseous substances under

pressure where it is necessary to dilutethe burning gas at a very fast rate with

an inert gas or powder.

Carbon dioxide dry chemical

powder. The best way toextinguish such fires is by

stopping the flow of fuel gas

to the fire. Container is

kept cool with water spray

2878-1976

2171-1976

(4308)-1982

D Fires involving metals like magnesium,aluminum, zinc, potassium etc. where

the burning metal is reactive to water

and which require special extinguisher

media or technique

Special dry powder 2171-1976(4861)

1968

*As per IS:21901979


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AREA CLASSIFICATIONAREA CLASSIFICATION

Area classification is an assessment of dangerous atmospherewhere there is possibility of release of a flammable substance inrelation to a possible source of ignition from electrical

instruments, equipments or static electricity. The aim is to reducethe probability of these risks to the minimum.

Hazardous area are divided into three zone

Zone 0 Area: An area in which a flammable atmosphere is presentcontinuously, or is present for long periods.

Zone 1 Area: An area in which a flammable atmosphere is likely tobe present periodically or occasionally during normal operation.

Zone 2 Area: An area in which a flammable atmosphere is likely tooccur in normal operation and if it does occur it will exist for ashort time only.

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Storage and Classification Chemicals