Firefighter I6–5 Fire Classifications Class A fires Involve ordinary combustibles – Easily extinguished with water, water-based agents (foam), dry chemicals – Water most common agent used by fire service (Continued)
Firefighter I6–6 Fire Classifications Class B fires Involve flammable/ combustible liquids, gases, greases – Special fire hazards; should not be extinguished until fuel gas shut off – Special-hazard fires get larger as fuel volume increases – Extinguishing agents include carbon dioxide, dry chemical, Class B foam (Continued)
Firefighter I6–7 Fire Classifications Class C fires Involve Class A or B fires created by electrical energy – Do not use water, water-based agents until electrical energy eliminated – Recommended method is to turn off or disconnect electrical power before using appropriate extinguisher (Continued)
Firefighter I6–8 Fire Classifications Class D fires Involve combustible metals, alloys – Can be identified by bright white emissions from combustion process – Class D, dry powder extinguishers work best (Continued)
Firefighter I6–9 DISCUSSION QUESTION Why should water-based agents not be used on Class D fires?
Firefighter I6–10 Fire Classifications Class K fires Involve combustible cooking oils – Examples are vegetable fats that burn at extremely high temperatures – Most fuels found in commercial kitchens; can also be found in private homes – Wet chemicals used in extinguishing systems
Firefighter I6–11 Pump-Type Water Extinguishers Intended for use on small Class A fires only All operate in similar manner Equipped with single- or double-acting pump
Firefighter I6–12 Stored-Pressure Water Extinguishers Air-pressurized water extinguishers or pressurized water extinguishers Useful for all types of small Class A fires (Continued)
Firefighter I6–13 Stored-Pressure Water Extinguishers Often used for extinguishing hot spots Operation – Water stored in tank w/air or nitrogen – Gauge shows pressurization – Pressure forces water up tube, out hose Class A foam concentrate sometimes added
Firefighter I6–14 Water-Mist Stored-Pressure Extinguishers Use deionized water as agent, nozzles produce fine spray instead of stream Deionized water makes safe for use on energized electrical equipment Fine spray enhances cooling/soaking characteristics, reduces scattering of burning material
Firefighter I6–15 Wet Chemical Stored-Pressure Extinguishers Specifically designed to control/extinguish Class K fires in deep fryers Contain special potassium- based alkaline agent to cool/suppress fires in unsaturated cooking oils Courtesy of Ansul Corp.
Firefighter I6–16 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 (Continued)
Firefighter I6–17 Aqueous Film Forming Foam (AFFF) Extinguishers 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 (Continued)
Firefighter I6–18 Aqueous Film Forming Foam (AFFF) Extinguishers When AFFF/water mixed, finished foam floats on fuels lighter than water Vapor seal created by film of water extinguishes flame, prevents reignition (Continued)
Firefighter I6–19 Aqueous Film Forming Foam (AFFF) Extinguishers 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
Firefighter I6–20 Clean Agent Extinguishers Designed as replacement for Halon 1211, use clean agents that discharge as rapidly evaporating liquids that leaves no residue – Cool/smother fires in Class A, B fuels – Nonconductive so can be used on Class C – Approved by U.S. EPA
Firefighter I6–21 Carbon Dioxide (CO 2 ) Extinguishers Found as both handheld/wheeled units Most effective in Class B, C fires Have limited reach; gas can be dispersed by wind (Continued) Courtesy of Ansul Corp.
Firefighter I6–22 Carbon Dioxide (CO 2 ) Extinguishers Carbon dioxide stored under its own pressure as liquefied gas ready for release at any time Wheeled units similar to handheld except wheeled are considerably larger Courtesy of Badger Fire Protection.
Firefighter I6–23 DISCUSSION QUESTION What is the danger of touching the horn on a carbon dioxide extinguisher shortly after it has been used?
Firefighter I6–24 Dry Chemical Extinguishers For Class A-B-C fires and/or Class B-C fires; dry powder used on Class D only Commonly used today (Continued) Courtesy of Ansul Corp.
Firefighter I6–25 Dry Chemical Extinguishers Two basic types – Regular B:C-rated – Multipurpose and A:B:C- rated Commonly used dry chemicals Handheld units Wheeled units Courtesy of Ansul Corp.
Firefighter I6–26 DISCUSSION QUESTION What happens when water is applied to a combustible metal fire?
Firefighter I6–27 Controlling/Extinguishing Metal Fires Special extinguishing agents, application techniques developed to control/extinguish metal fires No single agent controls/extinguishes fires in all combustible metals (Continued)
Firefighter I6–28 Controlling/Extinguishing Metal Fires Some powdered agents applied with portable extinguishers, others with shovel or scoop Appropriate application technique described in manufacturers technical sales literature (Continued)
Firefighter I6–29 Controlling/Extinguishing Metal Fires Portable extinguishers for Class D come in both handheld, wheeled units (Continued) Courtesy of Amerex Corp.
Firefighter I6–30 Controlling/Extinguishing Metal Fires Regardless of applicator, powder must be applied in sufficient depth to completely cover burning area to create smothering blanket (Continued)
Firefighter I6–31 Controlling/Extinguishing Metal Fires If small amount of burning metal on combustible surface, fire should be covered with powder 1 to 2 inch (25 to 50 mm) layer spread nearby, burning metal shoveled onto layer After extinguishment, material left undisturbed until cooled
Firefighter I6–32 Portable Extinguisher Rating System Portable extinguishers classified according to types of fire they extinguish Class A, B also rated according to performance capability System based on tests by UL, ULC
Firefighter I6–33 Classifications Class A From 1-A through 40-A Class B From 1-B through 640-B Class C No tests Class D Test fires vary Class K Recognized by UL, ULC since 1996
Firefighter I6–34 Multiple Markings Extinguishers for more than one class of fire identified by combinations of A, B, and/or C or symbols for each class – Most common are A-B-C, A-B, B-C – All must be labeled appropriately – Unlisted units should not be used – Ratings for each class are independent
Firefighter I6–35 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
Firefighter I6–36 Extinguisher Selection Factors Classification of burning fuel Rating of extinguisher Hazards to be protected Size/intensity of fire (Continued)
Firefighter I6–37 Extinguisher Selection Factors Atmospheric conditions Availability of trained personnel Ease of handling extinguisher Life hazard/operational concerns
Firefighter I6–38 Extinguisher Selection Considerations Select those that minimize risk to life/ property and are effective in extinguishing the fire type Dry chemical extinguishers should not be selected for use in areas where highly sensitive computer equipment is located
Firefighter I6–39 Extinguisher Check Immediately before use – External condition – Hose/nozzle – Weight – Pressure gauge After selecting size/type for situation, approach fire from windward side
Firefighter I6–40 DISCUSSION QUESTION Why should you always have an escape route?
Firefighter I6–41 Fire Extinguisher Operation All modern extinguishers operate in similar manner Pick up extinguisher by handles, carry to point of application (Continued)
Firefighter I6–42 Fire Extinguisher Operation Once in position, use PASS method – P Pull the pin – A Aim the nozzle – S Squeeze handles together – S Sweep nozzle back and forth (Continued)
Firefighter I6–43 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 for final extinguishment (Continued)
Firefighter I6–44 Fire Extinguisher Operation If extinguishment not achieved after entire extinguisher discharged, withdraw/reassess If fire is in solid fuel reduced to smoldering phase, may be overhauled using appropriate tool (Continued)
Firefighter I6–45 Fire Extinguisher Operation 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 and maintain constant awareness
Firefighter I6–46 Fire Extinguisher Inspections NFPA ® 10 and most fire codes require portable extinguishers inspected at least once/year Verify that extinguishers – Are in designated locations – Not tampered with or activated – No obvious damage/other condition (Continued)
Firefighter I6–47 Fire Extinguisher Inspections Servicing responsibility of property owner/building occupant Firefighters should include inspections in building inspection program (Continued)
Firefighter I6–48 Fire Extinguisher Inspections Three factors determine value – Serviceability – Accessibility – Simplicity of operation NFPA ® 10 describes procedures for hydrostatic testing of cylinders
Firefighter I6–49 Parts of Fire Extinguisher Inspections Ensure extinguisher in proper location/accessible Inspect discharge nozzle Inspect extinguisher shell Check for legible operating instructions on nameplate INACCESSIBLE (Continued)
Firefighter I6–50 Parts of Fire Extinguisher Inspections Check locking pin, tamper seal Determine whether full of agent, fully pressurized Check for date of previous inspection Examine condition of hose/fittings If any items deficient, remove from service
Firefighter I6–51 Damaged Fire Extinguishers Can fail at any time; could result in serious injury Leaking, corroded, otherwise damaged shells/cylinders should be discarded or returned to manufacturer for repair (Continued)
Firefighter I6–52 DISCUSSION QUESTION How should a defective fire extinguisher be repaired?
Firefighter I6–53 Damaged Fire Extinguishers Only slight damage/corrosion and uncertain whether safe Should be hydrostatically tested If allowed by SOP, leaking hoses, gaskets, nozzles, and loose labels can be replaced by firefighters
Firefighter I6–54 Obsolete Portable Fire Extinguishers In 1969 – American manufacturers stopped making inverting-type extinguishers – Manufacturing of extinguishers made of copper or brass with cylinders soft soldered or riveted together discontinued (Continued)
Firefighter I6–55 Obsolete Portable Fire Extinguishers Extinguishers using carbon tetrachloride and chlorobromomethane prohibited in workplace If obsolete extinguishers are discovered and occupant requests, firefighters should follow SOP to dispose of them
Firefighter I6–56 Halon Fire Extinguishers Included in Montreal Protocol U.S. stopped producing halogens at end of 1993 Units may still be in service
Firefighter I6–57 Summary In many cases, fire extinguishers can control or extinguish small fires in less time than it takes to deploy a hoseline. (Continued)
Firefighter I6–58 Summary Even though portable fire extinguishers may be found in many of the homes, apartments, and businesses that must be entered to extinguish fire, firefighters should only rely on those carried on the fire apparatus. (Continued)
Firefighter I6–59 Summary To use fire extinguishers safely and effectively, firefighters must know capabilities and limitations of the extinguisher and their own capabilities and limitations as well as the proper techniques for their application.