Chapter 6 Portable Fire Extinguishers

Fire Extinguishment Methods

• Smothering

• Cooling

• Chain breaking

• Saponification

Fire Classifications• Class A fires — Involve ordinary combustibles

– Easily extinguished with water• Class B fires — Involve flammable/combustible

liquids, gases, greases– Special fire hazards; should not be extinguished until fuel gas

shut off– fires get larger as fuel volume increases– Extinguishing agents: carbon dioxide, dry chemical, Class B foam

• Class C fires — Involve Class A or B fires created by electrical energy– Do not use water until electrical energy eliminated– Turn off or disconnect electrical power - it becomes a class A fire

• Class D fires — Involve combustible metals, alloys– Water can make combustion worse– Class D, dry powder extinguishers work best

• Class K fires — Involve combustible cooking oils– Animal and vegetable fats that burn at extremely high

temperatures

Stored-Pressure Water Stored-Pressure Water ExtinguishersExtinguishers

Air-pressurized water extinguishers or Air-pressurized water extinguishers or pressurized water extinguisherspressurized water extinguishers

Useful for all types of small Class A firesUseful for all types of small Class A fires Often used for extinguishing hot spotsOften used for extinguishing hot spots OperationOperation

Water stored in tank with airWater stored in tank with air Gauge shows pressurizationGauge shows pressurization Pressure forces water up tube, out hosePressure forces water up tube, out hose

Class A foam concentrate sometimes Class A foam concentrate sometimes addedadded

Wet Chemical Stored-Wet Chemical Stored-Pressure ExtinguishersPressure Extinguishers

Contain special potassium-based low-Contain special potassium-based low-pH agent to cool/suppress fires in pH agent to cool/suppress fires in unsaturated cooking oilsunsaturated cooking oils

Specifically designed to Specifically designed to control/extinguish Class K fires in deep control/extinguish Class K fires in deep fryersfryers

SaponificationSaponification

Aqueous Film Forming Foam (AFFF) Extinguishers

• Suitable for Class A, Class B fires• Fires/vapors from small liquid fuel spills• Different from stored-pressure water extinguishers

– Tank contains specified amount of AFFF concentrate mixed with water

– Air-aspirating nozzle aerates solution

• Water/AFFF solution expelled by compressed air or nitrogen

• To prevent disturbance of foam blanket, do not apply directly onto fuel; allow to rain onto surface/deflect off object

AFFF• When AFFF/water mixed, finished foam floats on

fuels lighter than water• Vapor seal created by film of water extinguishes

flame, prevents reignition• Foam has good wetting, penetrating properties

on Class A fuels; ineffective on polar solvents• Not suitable for fires in Class C, D fuels• Most effective on static pools of flammable

liquids

Clean Agent Clean Agent ExtinguishersExtinguishers

Designed as replacement for Halon 1211, Designed as replacement for Halon 1211, use “clean agents” that discharge as use “clean agents” that discharge as rapidly evaporating liquids that leaves no rapidly evaporating liquids that leaves no residueresidue Cool/smother fires in Class A, B fuelsCool/smother fires in Class A, B fuels Nonconductive so can be used on Class CNonconductive so can be used on Class C Approved by U.S. EPAApproved by U.S. EPA

Carbon Dioxide (COCarbon Dioxide (CO22) ) ExtinguishersExtinguishers

Found as both handheld/wheeled unitsFound as both handheld/wheeled units Most effective in Class B, C firesMost effective in Class B, C fires Have limited reach; gas can be dispersed by Have limited reach; gas can be dispersed by

windwind Carbon dioxide stored under Carbon dioxide stored under

its own pressure as liquefied its own pressure as liquefied gas ready for release at any gas ready for release at any timetime

Dry Chemical ExtinguishersDry Chemical Extinguishers

For Class A-B-C fires and/or Class B-C For Class A-B-C fires and/or Class B-C fires; dry powder used on Class D onlyfires; dry powder used on Class D only

Commonly used todayCommonly used today Two basic typesTwo basic types

Regular B:C-ratedRegular B:C-rated Multipurpose and A:B:C-ratedMultipurpose and A:B:C-rated

Commonly used dry chemicalsCommonly used dry chemicals Handheld unitsHandheld units Wheeled unitsWheeled units

Controlling/Extinguishing Metal Fires

• Special extinguishing agents, application techniques developed to control/extinguish metal fires

• No single agent controls fires in all combustible metals• Some powdered agents applied with extinguishers, others with shovel• Portable extinguishers for Class D come in both handheld, wheeled

units• Regardless of applicator, powder must be applied in sufficient depth

to completely cover burning area to create smothering blanket• Operation

– If small amount of burning metal on combustible surface, fire should be covered with powder

– 1 to 2 inch layer spread nearby, burning metal shoveled onto layer– After extinguishment, leave material undisturbed until cooled

• Burning Magnesium

Portable Extinguisher Portable Extinguisher Rating SystemRating System

Portable extinguishers classified Portable extinguishers classified according to types of fire they extinguishaccording to types of fire they extinguish

Class A, B also rated according to Class A, B also rated according to performance capabilityperformance capability

System based on tests by System based on tests by UL, ULCUL, ULC A: Cubic feetA: Cubic feet B: Square feetB: Square feet

ClassificationsClassifications

Class A Class A — F— From 1-A through 40-Arom 1-A through 40-A Class B Class B — From 1-B through 640-B— From 1-B through 640-B Class C — Conductivity onlyClass C — Conductivity only Class D — Specific to materialClass D — Specific to material Class K — Recognized by UL, ULC since Class K — Recognized by UL, ULC since

19961996

Multiple MarkingsMultiple Markings

Extinguishers for more than one class of Extinguishers for more than one class of fire identified by combinations of A, B, fire identified by combinations of A, B, and/or C or symbols for each classand/or C or symbols for each class Most common are A-B-C, A-B, B-CMost common are A-B-C, A-B, B-C All must be labeled appropriatelyAll must be labeled appropriately Unlisted units should not be usedUnlisted units should not be used Ratings for each class are independentRatings for each class are independent

Identification — Two Ways

• Geometric shapes of specific colors with class letter shown within shape

• NFPA 10 recommended: Uses pictographs to make selection easier; shows types of fires on which extinguishers should not be used

Extinguisher Selection Extinguisher Selection FactorsFactors

Classification of burning fuelClassification of burning fuel Rating of extinguisherRating of extinguisher Hazards to be protectedHazards to be protected Size/intensity of fireSize/intensity of fire

Atmospheric conditionsAtmospheric conditions Availability of trained personnelAvailability of trained personnel Ease of handling extinguisherEase of handling extinguisher Life hazard/operational concernsLife hazard/operational concerns

Extinguisher Selection Extinguisher Selection ConsiderationsConsiderations

Select those that minimize risk to life/Select those that minimize risk to life/property and are effective in property and are effective in extinguishing the fire typeextinguishing the fire type

Dry chemical extinguishers should not be Dry chemical extinguishers should not be selected for use in areas where highly selected for use in areas where highly sensitive computer equipment is locatedsensitive computer equipment is located

Extinguisher CheckExtinguisher Check

Immediately before useImmediately before use External conditionExternal condition Hose/nozzleHose/nozzle WeightWeight Pressure gaugePressure gauge

After selecting size/type for situation, After selecting size/type for situation, approach fire from windward sideapproach fire from windward side

PASS Method

Fire Extinguisher Operation• Be sure agent reaches fire• Apply agent from point where stream

reaches but does not disturb fuel• After fire knocked down, move closer to

achieve final extinguishment• If extinguishment not achieved after entire

extinguisher discharged –You screwed up!• If fire is in solid fuel reduced to smoldering

phase, may be overhauled using appropriate tool

• If fire in liquid fuel, it may be necessary to apply foam through hoseline or simultaneously attack with more than one extinguisher

• If more than one extinguisher used simultaneously, work in unison

Fire Extinguisher InspectionsFire Extinguisher Inspections NFPANFPA 10 and most fire codes require portable 10 and most fire codes require portable

extinguishers inspected once a yearextinguishers inspected once a year Verify that extinguishersVerify that extinguishers

Are in designated locationsAre in designated locations Not tampered with or activatedNot tampered with or activated No obvious damage/other conditionNo obvious damage/other condition

Servicing is the responsibility of property owner/building Servicing is the responsibility of property owner/building occupantoccupant

Firefighters should include inspections in building Firefighters should include inspections in building inspection programinspection program

Three factors determine valueThree factors determine value ServiceabilityServiceability AccessibilityAccessibility Simplicity of operationSimplicity of operation

NFPANFPA 10 describes procedures for hydrostatic testing of 10 describes procedures for hydrostatic testing of cylinderscylinders

Parts of Fire Extinguisher Parts of Fire Extinguisher InspectionsInspections

Ensure extinguisher in proper location/accessibleEnsure extinguisher in proper location/accessible Inspect discharge nozzleInspect discharge nozzle Inspect extinguisher shellInspect extinguisher shell Check for legible operating instructions on Check for legible operating instructions on

nameplatenameplate Check locking pin, tamper sealCheck locking pin, tamper seal Determine whether full of agent, fully pressurizedDetermine whether full of agent, fully pressurized Check for date of previous inspectionCheck for date of previous inspection Examine condition of hose/fittingsExamine condition of hose/fittings If any items deficient, remove from service If any items deficient, remove from service

Damaged Fire Damaged Fire ExtinguishersExtinguishers

Can fail at any time; could result in serious Can fail at any time; could result in serious injury injury Exploding Fire Extinguisher Exploding Fire Extinguisher

Leaking, corroded, otherwise damaged Leaking, corroded, otherwise damaged shells/cylinders should be discarded or shells/cylinders should be discarded or returned to manufacturer for repairreturned to manufacturer for repair

Only slight damage/corrosion and uncertain Only slight damage/corrosion and uncertain whether safe — Should be hydrostatically whether safe — Should be hydrostatically testedtested

If allowed by SOP, leaking hoses, gaskets, If allowed by SOP, leaking hoses, gaskets, nozzles, and loose labels can be replaced by nozzles, and loose labels can be replaced by firefightersfirefighters

Obsolete Portable Fire Obsolete Portable Fire ExtinguishersExtinguishers

In 1969In 1969 American manufacturers stopped making inverting-type American manufacturers stopped making inverting-type

extinguishersextinguishers Manufacturing of extinguishers made of copper or brass Manufacturing of extinguishers made of copper or brass

with cylinders soft soldered or riveted together with cylinders soft soldered or riveted together discontinueddiscontinued

Extinguishers using carbon tetrachloride and Extinguishers using carbon tetrachloride and chlorobromomethane prohibited in workplacechlorobromomethane prohibited in workplace

If obsolete extinguishers are discovered and If obsolete extinguishers are discovered and occupant requests, firefighters should follow SOP to occupant requests, firefighters should follow SOP to dispose of themdispose of them

Halon Fire ExtinguishersHalon Fire Extinguishers

Included in Montreal ProtocolIncluded in Montreal Protocol U.S. stopped producing halogens at end U.S. stopped producing halogens at end

of 1993of 1993 Units may still be in serviceUnits may still be in service

On Your Face!!!