Fire Triangle

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OBJECTIVES: 1. Understand the combustion process. 2. Understand the classification of Fire. 3. Principle of fire extinguishm extinguishment. ent. 4. Understand

fire extinguisher types, operating procedures, capabilities and limitations.  

 

BASICS OF FIRE FIRE 

Fire, also known as combustion, is the process of rapid oxidation at high temperatures. This releases hot gases, light, and invisible forms of radiation energy.

Three elements are necessary for initiation of fire: 1. Fuel in the form of vapour, vapour, liquid or solid. 2. A source of ignition sufficient to initiate & propagate the fire. fire. 3. Oxygen in sufficient proportion to form a combustible mixture.

   

BASICS OF FIRE FIRE TRIANGLE

SMOOTHERING

FIRE TETRAHEDRON

COOLING

STARVATION



Removal of any side of the triangle or breaking the chain reaction between the transient chemical species formed following ignition will extinguish a fire.

 

BASICS OF FIRE Combustion process is observed in two modes. For flaming combustion    to occur, solid or liquid fuel must be converted into a vapour, which then mixes air and reacts with oxygen. Smoldering combustion  , on the other hand, involves a reaction

between oxygen and the surface surface of the fuel:

this is a complex

process and in general occurs with solid fuels which char on heating.

 

BASICS OF FIRE Principle of Extinguishment of Fire  

Fire extinguishment involves removal or limiting of one or more of the factors described by the fire triangle. The method of extinguishment of fire may be classified under the following heads: Starvation

: Elimination Of Fuel

Smothering Cooling Chain Breaking

: Limiting Oxygen Supply : Limiting Rise Of Temp. : Limiting Chain Carriers

 

BASICS OF FIRE Removal of Fuel 

The removal of fuel is not always possible. However, in the case of liquid fuel fires caused by leaking pipes or fittings, the fuel supply should be closed.



It may also be possible to drain the fuel from a burning tank.



It is particularly important to shut off the supply in a gas fire. However, gas could also be left burning in a controlled manner to exhaust itself.



In accommodation spaces, combustible materials should be removed from the vicinity of fire, including any adjacent compartment affected by the heat.

 

BASICS OF FIRE Removal of Heat 

A reduction in temperature is achieved by the use of a suitable cooling medium, normally water, water, at a sufficient rate. rate .



Cooling of boundary bulkheads will reduce the possibility of igniting material outside the affected compartment.



Heat can also be absorbed by decomposition of dry powder. The source of power should be cut off in electrical insulation.

 

BASICS OF FIRE Removal of Oxygen 

Except in those substances that contain their own oxygen, the removal of sufficient oxygen will extinguish a fire.



In fire extinguishing operations, oxygen is extinguished by smothering the fire with a layer of foam.



Oxygen is also cut off during the operation of portable and semi portable carbon dioxide extinguishers and to some extent, during he operation of dry powder extinguishers.



But for CO2 and dry powder, the smothering action is temporary and there is a possibility for re- ignition.

 

BASICS OF FIRE Fi re Tetrahed The Fire Tetrahedron ron Model 

Fire requires four elements in order to start and continue to burn.



The forth element of fire is a self-sustaining chemical reaction called "combustion" that produces continued heat that serves to keep the fire fi re burning.



To help illustrate that these four elements must occur together in order for a fire to exist, the 4-sided pyramidal shaped tetrahedron model was developed.



Remove any one of these elements from the fire tetrahedron and the fire will not start or, if already burning, will be extinguished.   extinguished.

 

BASICS OF FIRE Breaking the Chain Reaction 

A fire may be extinguished by breaking the chain reaction between momentary chemical species (radicals) produced on ignition (these species are described as 'transient' since they are not present prior to ignition or in the final products of

combustion).  For instance, Halogenated hydrocarbons (Halons) and dry powders attack the structure of the species and prevent their reaction by killing the flame, sometimes in less than one hundre hundredth dth of a second. The destruction takes place without any appreciable removal of heat, fuel or oxygen.  However, the remaining three sides of the tetrahedron will still be present and, unless the heat is removed, there is a danger of re-ignition of the concentration of extinguishing agent is not 

maintained.   maintained.  

BASICS OF FIRE Free Radical Reaction during fire:

The term "free radical" or "radical" is used to mean an atom or group in which one of the bonding orbitals is occupied by a single electron. Radicals are normally uncharged.

 

BASICS OF FIRE Extinguishment Mechanism Of DCP 

Sodium Bicarbonate Whenof the DCPflame enters the combustion it decomposes by the :heat to liberate water, waterzone, vapours and carbon dioxide. 2 NaHCO3



------- Na2CO3 + H2O + CO2

The sodium Carbonate further decomposes to give Na2CO3 -------- Na2O + CO  Na2O --------- 2NaOH (in presence of H radicals)



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



Also NaO + H -------



NaOH

Na + OH ------- NaOH  This way all the H and OH radicals in fire are removed by breaking the chain

reaction and thus extinguish the fire.  

BASICS OF FIRE Different Fire Extinguishing Media: 

Sand



Water



Dry Chemical Powder



Inert Gas



CO2 Gas



Steam



AFFF (Aqueous Film Forming Foam)/ ARFFF



Clean Agent Agent System (FM-200)

 

BASICS OF FIRE Types of Fire Extinguishers Water  The Water Extinguisher extinguishes the fire by cooling the fuel below its ignition temperature.  Water is very effective cooling medium also easily available everywhere.  The water extinguisher is very effective on A class fires but is ineffective and dangerous on other classes of fire.  It must not be used on electrical fires as water is an excellent conductor of electricity. Carbon Dioxide  Carbon Dioxide (C02) is a colourless, odourless, and tasteless gas that is heavier than air and does not support life. It is not a toxic gas.  The CO2 extinguisher relies on its ability to displace or dilute

the Oxygen around the burning material smothering the fire.  

BASICS OF FIRE Dry Chemical Powder  



The Dry Chemical Powder (DCP) fire extinguisher is probably the most versatile extinguisher available today. today. DCP extinguishers extinguish fires by smothering, and interfering with the chemical chain reaction of burning. They provide a rapid knockdown on a range of fires. DCP mainly contains Potassium or Sodium Bicarbonate with stabilizers.

Foam Fire Extinguisher   

The extinguisher suitable for the extinguishments of class Foam B (flammable liquid)isfires. Foam provides a lasting blanket, which floats on the burning fuel and smothers the fire. In addition to its ability to extinguish fires, the foam extinguisher can be used as a vapour suppression barrier over

spills of flammable liquids.    

Classes of fire:

BASICS OF FIRE

Class A fires - are fires involving organic solids (like paper, paper, wood, coal, cloths, dry grass etc.) Best Extinguish Extinguishing ing media-water Class B fires - are fires involving flammable Liquids (like Petrol, diesel, kerosene, naphtha etc.) Best Extinguishing media-foam, media-foam , carbon dioxide, DCP Class C fires - are fires involving flammable Gasses (like LPG, CNG, NG, H2 gas etc.) Extinguishing media - Carbon dioxide, dioxide, DCP. DCP. The best way to extinguish such fires is by stopping stop ping the flow of fuel gas to fire. Container is kept cool with water spray. spray. Class D fires -  - Fires involving metals like magnesium, aluminum, zinc, potassium etc. Where the burning metal is reactive to water and which require special extinguishing media. (like Na, K, Mg, M g, Al etc.)

Extinguishing media- special dry powder.  

BASICS OF FIRE Classification of Fire A

Ordinary Combustible Material •

wood



Cloth



Paper



Rubber



B



H  2



sodium

grease



potassium

tar



titanium



zirconium



other

oil







LPG

magnesium









gasoline



Flammable Gases

Many plastics   



Flammable Liquids

C

oil-based paint lacquer flammable gases

D Combustible Metal

flammable metals

gases

D

 

BASICS OF FIRE 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.

 

BASICS OF FIRE Common Fire Definitions: Backdraft -- The beginning of a backdraft occurs from a fire in a structure being poor presence of necessary oxygen. The fire smolders giving off unburned carbon particles and other flammable products. Then, the smoldering fire is given a sudden speeds influx of oxygen causingsuddenly combustion to restart possibly at devastating consistent with an explosion. Flash Point -- The minimum temperature at which a liquid fuel gives off

sufficient vapors to form an ignitable mixture with the air near the surface. At this temperature, the ignited vapors will flash but will not continue to burn. Ignition Temperature -- The minimum temperature to which a fuel in air must be heated to start self sustained combustion without a separate

ignition source.  source.   

BASICS OF FIRE Explosive limits •

Explosive limits are those concentrations of a vapor or gas in air below or above which propagation of a flame does not occur on contact with a source of ignition.



The L owe werr Explos Explosive ive L imi t (L EL )    is the minimum concentration below which the vapor air mixture is too lean to burn or explode.



The Uppe Upperr Ex Explos plosii ve L i mit (UEL (U EL ) is the maximum concentration above which the vapor air mixture is too rich to burn or explode.

 

BASICS OF FIRE

 

BASICS OF FIRE

 

BASICS OF FIRE Classification of Petroleum Products Class –  Class  –  a : liquid which have flash point below 23oc. Class –  Class  –  b :

liquids which have flash point of 23oc and above but o

Class –  Class  –  c :

below 65 c liquid which have flash point of 65oc and above but

below 93oc.  

o

Excluded petroleum : liquid which have flash point of 93 c and above. LPG do not fall under this classification but form separate category. category.

   

AUTO IGNITION, FLASH POINT AND EXPLOSIVE LIMITS OF SOME OF THE PETROLEUM PRODUCTS O

S. NO.

MATERIAL MA TERIAL

AUTO IGNITION IGNITIO NoC TEMPERATURE

FLASH POINT C

EXPOSING VOLUME % IN AIR LOWERRANGE LIMIT UPPER LIMIT

1

CRUDE OIL

DEPENDS UPON THE NATURE OF CRUDE

19

DEPENDS UPON THE NA NATURE TURE OF CRUDE LEL

UEL

2.

HYDROGEN

585

GAS

4.1

74.0

3

METHANE

538

GAS

5.0

15.0

4

ETHANE

514

GAS

3.0

12.5

5

PROPANE PROP ANE

466

GAS

2.4

9.5

6

BUTANE BUT ANE

430

GAS

1.5

9.0

7

BENZENE

563

-11

1.3

7.1

8

TOLUENE

536

4.5

1.2

7.2

9

NAPHTHA

288

-18

1.1

5.9

10

GASOLINE

245

-7

1.4

7.6

11

ATF

254.4

38

0.7

5

12

SKO

254

35

0.7

5

 

AUTO IGNITION, FLASH POINT AND EXPLOSIVE LIMITS OF SOME OF THE PETROLEUM PRODUCTS

S. NO.

MATERIAL MA TERIAL

AUTO IGNIT IGNITION ION FLASH OC TEMPERATURE

13

HSD

256

32

0.7

5

14

LDO

-

66

-

-

15 16

LSHS HSHS

316 -

66-166 65.6-148.9

-

-

17

FO

262-407

-

-

-

18

BITUMEN

485

205

-

-

19 20

RAW COKE RAW PHENOL EXTRACT

715

315.6 80

-

-

21

SLACK WAX

245

198.9

-

-

22

MINERAL TURPENTINE OIL

253.3

32.2

-

-

23

LPG

405-450

GAS

1.8

9.6

POINT EXPOSING RANGE VOLUME % IN AIR LOWER LIMIT UPPER LIMIT

 

MAJOR REFINERY POTENTIAL HAZARDS



FIRE HAZARD



EXPLOSION HAZARD



ELECTRICAL HAZARD



TOXIC GAS RELEASE HAZARD



HAZARDOUS CHEMICAL HAZARD



OIL SPILLAGE



RADIATION HAZARD



FALL FROM HEIGHT

 

SOURCE OF IGNITION IT IS INITIAL RELEASE OF ENERGY TO TRIGGER COMBUSTION (FIRE). IT IS NECESSARY TO UNDERSTAND THE SOURCES OF IGNITION AND TO ELIMINATE THEM TO PREVENT FIRES/EXPLOSIONS FIRES/ EXPLOSIONS IN OUR REFINERY REFINERY.. SOURCES OF IGNITION

EXAMPLE

PREVENTIVE MEASURES

ELECTRICAL EQUIPMENT

SPARKS FROM MOTORS, 1. USE OF APPRO APPROVED VED EQUIPM EQUIPMENT ENT SWITCHES, LAMPS, HOT 2. FOLLOW NA NATION TION ELECTRICA ELECTRICAL L ELEMENTS AND CODES ELECTRICAL DEFECTS 3. PROP PROPER ER MAINT MAINT.

FRICTION

HOT BEARINGS, MIS- PREVENTIVE MAINT. AND PROPER ALLIGNED OR BROKEN LUBRICATION M/C PARTS, CHOCKING, JAMMING OF MATERIAL, POOR ADJUSTMENT

OPEN FLAMES

CUTTING OF TORCHES AND GAS WELDING & OIL STRICT PRECAUTIONS COMPLIANCE STIPULATED IN THE

BURNERS

FIRE PERMIT FOR HOT JOBS.

 

SOURCE OF IGNITION

SOURCES OF IGNITION SMOKING IGNITION

EXAMPLE

PREVENTIVE MEASURES

AS SMOKING BOOTHS IN 1. SM SMOKI OKING NG ONLY ONL Y IIN N AREAS AREA S AREA WHERE PERMITTED. COMBUSTIBLE ARE USED 2. US USE E OF FOR PRES OF PR ESCR CRIB IBED ED RECEPTACLES CIGARETTE BUTTS

SPONTANEOUS IGNITION

PYROPHORIC IRON, HOT 1. KE KEEP EP PYR PYROPH OPHOR ORIC IC IRO IRON N WET WET ARE ARE OIL LEAKAGE THE TIME WHEN IT IS TAKEN OUT.

HOT SURF SURFACES ACES

CONTACT CONTACT OF 1. PRO PROVID VIDE E PROPER PROPER INS INSUL ULA ATIO TION N COMBUSTIBLE MATERIAL AND AIR CIRCULA CIRCULATION. TION. WITHOUT SURFACES, HEATED LINES

SPARK

FROM POL TRUCKS / DG SET

1. SP SPARK ARK ARREST ARRESTOR OR ON EXHAUST

ENGHINE EXHAUST  

SOURCE OF IGNITION

SOURCES OF IGNITION

EXAMPLE

STA ST ATIC ELECTRICITY

DURING SPLASH LOADING AND LOADING AT HIGH VELOCITIES

PREVENTIVE MEASURES 1. PROP PROPER ER EA EAR RTH THIN ING G OF OF EQUIPMENT. 2. DO NO NOT T RESO RESOR RT TO TO SPLA SPLASH SH LOADING 3. LOADI LOADING NG VEL VELOCI OCITY TY SHO SHOUL ULD D BE CONTROLLED

LIGHTENING

THUNDERSTORM CLOUD BURST

1. PRO PROPER PER LIGHT LIGHTIN ING G ARRES ARREST TOR AND AND EARTH CONTINUITY.

 

FIRE RISK MANAGEMENT



Fire risk is ‘The chance/possibility of loss due to fire’.



Three aspects to deal with fire risk management are: 

Fire Prevention



Fire Protection  – Active & Passive



Fire Fighting

 

FIRE PROTECTION IN GENERAL FIRE PREVENTION : IT MEANS ADOPTION OF SAFE INHERENT DESIGN AND PROVISIONS AT THE DESIGN STAGE INITIALLY AND SUBSEQUENTLY DEVELOPING SAFE PROCEDURE TO FOLLOW IN THE DAY DAY TO TO DAY DAY OPERATION. OPERATION. IT IS THE CONCERN OF EVERYBODY WORKING IN THE REFINERY REFINERY.. FIRE PROTECTION : IT INVOLVES OF DIFFERENT FACILITIES WHICH SHALL HELP IN IMMEDIATE HANDLING OF FIRE FIR E EFFECTIVELY EFFE CTIVELY.. FIRE FIGHTING : IT IS THE PHYSICAL PHENOMENON OF HANDLING THE FIRE WITH THE USE OF FIRE EQUIPMENTS, FACILITIES AS WELL AS WITH TRAINED THE HELPFOR OF FIRE PROTECTION FIGHTING PERSONNEL WHO HAVE BEEN SPECIFICALLY

THIS JOB.  

FIRE RISK MANAGEMENT Fire Prevention Objective : to eliminate the occurrence occurrence of fire fire 1. Fire Fire or nake naked d light, light, match matches, es, petr petrol ol or or other light lighters, ers, cellu cellular lar phone or any apparatus which is capable of causing ignition is not permitted to be taken within the battery area by any person. person. fires es shal shalll be lit and no match matches es igni ignited ted in any any part part of of the the 2. No fir battery area area unless unless a valid hot work permit has been obtained from the authorized fire permit signatories of the area and registered at the fire station. registered 3. Smo Smokin king g is pro prohib hibite ited d in all all parts parts of the the batte battery ry area area exce except pt in the smoking booths/locations duly approved for this purpose. 4. Cyc Cycle le lamps lamps,, other other tha than n dynamo dynamo oper operate ated d , are are not not allowe allowed d in the the refinery battery limits. The cyclist will switch off even the dynamo as soon as he enters the plant area.

   

5. Ordina Ord inary ry tor torche chess will willofnot be use used d with w ithin in the bat batter tery y area. ar ea. Fla Flame me proof torches/lamps approved manufacturers as supplied by the refinery, shall only be used. 6. All vehic vehicles les ente enterin ring g / transpo transporti rting ng petr petrole oleum um produ products cts from from the the refinery must be fitted only with approved type of spark arrestors.

   

Fire protection (Passive & Active) Following fire protection facilities shall be provided depending on the nature of the installation and risk involved: •

Fire water system



Foam system



Clean agent system

• •

CO2 system DCP extinguishing system



Detection and alarm system



Communication system

 

Passive fire protection system (at the time of construction & installation) 

  Dyke walls



  Safety valves on equipment

  Water seal in separat separators ors    Rupture disc in process piping 



  Fire proofing of structures

  Fire retardants paints on cables    Fire barriers 



  Positive pressur pressurization ization



  Flaring / venting

 

Fire fighting Objective : to extinguish the fire with minimum loss It is the last last line line of the defense. It comes comes into force force when there is actual fire. Main purpose is to extinguish extinguish the fire with suitable equipment and materials with an aim to reduce damage due to fire •  Portable fire fighting equipment •  Mobile fire fighting equipment •  Fixed fire fighting system

Active Fire Protection

   

Fire fighting Portable fire fighting equipment

(First Aid Fire Fighting Equipment)

• DCP Extinguishers. • CO2 extinguishers. • Water Extinguishers • Portable Foam Extinguishers. • Clean Agent Fire Extinguishers

 

Fire fighting Mobile fire fighting equipment Foam tenders • •

DCP tenders



Foam Nurser



Hydraulic Platform- 54 m height



Trailer fire pump



Trolley mounted monitors



Fire fighting hose & other accessories like foam branch, branch, nozzles etc.



Fire fighting chemicals like foam compound, dry chemical

powder etc.  

Fire fighting Fixed fire fighting equipment •

Fire Hydrants



Fire Monitors.



High Volume Long Range Monitors.



Riser



Sprinkler Systems



Foam Pourer Systems

 

DCP Extinguishers

 

Operating Mechanism Mechanism Of DCP

 

Dry Chemical Powder 

Class “A”, “B”, or “C” fires. 

A  Trash Wood Paper



B  Liquids

Grease



C

2-10 Kg. dry chemical (ammonium  phosphate) pressurized  phosphate)  pressurized to 3.5 –  14  14 kg/ sq. cm by CO2 gas (8-25 seconds discharge time). Has pressure gauge to allow visual capacity check.

Gases



1.5 –  6  6 m. maximum effective range.



Extinguishes by smothering  by smothering  burning  burning materials.

 

Carbon Dioxide (CO2) A  Trash Wood Paper



Class “B” or “C” fires. 



2 / 4.5 / 6.8 / 9 / 22.5 kg CO2 gas at 51 Kg/cm2. Has NO pressure gauge. Capacity verified by weight. 3-8 ft. maximum effective range. Extinguishes by smothering burning materials.

 B  Liquids

Grease

 

C

Gases



Effectiveness as temperature ofdecreases burning material increases.

Suitable Suita ble for Electrical Fire  

Method of Operation of DCP Fire Extinguishers (10 Kg)

(1)Squeeze the nozzle

(2) Remove Safety Clip

(3) Strike

on top of (4) Direct the discharge nozzle at the base of Fire in sweeping

the cap

action  

Method of Operation of CO2 Fire Extinguisher

(1)Hold the horn towards Fire (2) Remove Caution: On initial discharge of CO2 it may give electric shock momentarily . Don’t get panic. Open the operating knob intermittently.

Safety Pin

(3)Rotate knob in anti clock wise.

 

Precaution at the time of Fire Fighting •





Extinguishing agent eliminates eliminates one of the vital elements of the fire Many types of extinguishers available available



Know location of extinguishers Alarm has been sounded



Building has been evacuat evacuated ed



Fire is small and confined



You can fight the fire with your back toward an escape route



The extinguisher matches the fire type



The extinguisher works effectively



You are properly trained in the use of the t he extinguisher

You are confident you can put the fire out



 

Personal hazards •

Smoke Smok e and noxious fumes



Smoke Smok e and fumes cause unconsciousness



Burn

 

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