Portable Fire Extiguishers

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PORTABLE FIRE EXTINGUISHER

OBJECTIVE

Learning Outcome 6 Operate Portable Fire Extinguisher

Assessment Criteria 66.1 Identify the various types of fire extinguishing agents.

6.2 State the qualities and effectiveness on the classes of fire

6.3 Deploy the correct method of application.

6.4 Asses the compatibility of the different types of fire

extinguishing agents.

6.5 State the correct method of inspecting fire extinguisher.

REFERENCES

a. Fundamentals Of Fire Fighter Skills Chapter 7.b. Essentials of Fire Fighting Fourth Edition Edited By Richard Hall and Barbara Adams

Chapter 4.c. Firefighters Handbook Basic Essentials of Firefighting Chapter 8.


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PORTABLE FIRE EXTINGUISHER

INTRODUCTION

The portable fire extinguisher, one of the most comman fire-protection appliances in usetoday, is found in fixed facilities and or fire apparatus. A portable fire extinguisher is excellentto use on incipient fires. In many case, a portable fire extinguisher can extinguish a small firein much less time than it would take to deploy a hoseline. It is important that firefighter beknowledge able about the different types of portable fire extinguishers and their correct use.

THE VARIOUS TYPES OF FIRE EXTINGUISHING AGENTS

An extinguishing agent is the substance contained in a portable fire extinguisher that put outthe fire. Various different chemicals, including water, are used in portable fire extinguishers.The best extinguishing agent for the particular hazard depends on several factors, includingthe types of materials involved and the anticipated size of the fire. Portable fire extinguishers

use seven basic type of extinguishing agents:

Water

Dry Chemicals

Carbon Dioxide

Foam

Wet Chemicals

Halogenated agents

Dry Powder

Stored-Pressure Water Extinguishers

Stored-pressure water extinguishers, also called air-pressurized water (APW) extinguishers,are useful for all types of small Class A fires and are often use for extinguishers confined hotspots during overhaul operations, as well as for extinguishing chimney flue fires (Figure 6.3).Water is stored in a tank a along with either compressed air or nitrogen. A guage located onthe side of the valve assembly shows when the extinguisher is propely pressurized (Figure6.4). When the operating valve is activated, the water is forced up the siphon tube and outthrough the base (Figure 6.5). The procedures for operating stored-pressure extinguishersare listed in Skill Sheet 6-2.

Figure 6.3 : A typical stored-pressure Figure 6.4 : A pressure gauge

water extinguisher. clearly shows operable range.


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Figure 6.5 : Cutaway of a stored-pressure water extinguisher.

Aqueous Film Forming Foam (AFFF) Extinguishers

Aqueous film forming foam (AFFF) extinguishers are suitable for use on Class A and ClassB fires. They are particularly useful in combating fires or suppressing vapors on small liquidfuel spills. AFFF extinguishers are different from stored-pressure water extinguishers in twoways. The AFFF extinguisher tank contains a specified amount of AFFF concentrate mixedwith the water, and it has an air aspirating nozzle that aerates the foam solution, producing abetter quality foam than a standard extinguisher nozzle provides (Figure 6.6). Thewater/AFFF solution is expelled by compressed air or nitrogen stored in the tank with thesolution. To prevent the disturbance of the foam blanket when applying the foam, it shouldbe applied directly onto the fuel; it should be allowed to either gently rain down onto the fuelsurface or deflect off an object (Figure 6.7). When AFFF and water are mixed, the resultingfinished foam floats on the sirface of fuels that are lighter tahn water. The vapour seal

created by the film of water extinguishes the flame and prevents reiginition (Figure 6.8).

Figure 6.6 : A typical AFFF fire extinguisher.


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Figure 6.8 : The film of AFFF floatsahead of the foam blanket.

Figure 6.7 : Two ways in which AFFF can beapplied.

Halon Extinguishers

Hlaon is generic term for halogenated hydrocarbons and is defined as a chemical compoundthat contains carbon plus one or more elements from the halogen series (fluorine, chlorine,

bromine, or iodine). While a large number of halogenated compounds exist, only a few areused to a significant extent as fire extinguishing agents. The two most comman ones areHalon 1211 (bromochlorodifluoromethane) and Halon 1301 (bromotrifluoromethane).Although the halons have long been used for the protection of internal combustion engines,their primary modern-day application is for the protection of sensitive electronic equipmentsuch as computers.

Halon 1211 Halon 1211 extinguishers are intended primarily for use onClass B and Class C fires (Figure 6.9). Halon 1211 is storedin the extinguisher as a liquefied compressed gas, but nitrogenis added to the tank to increase discharge pressurevandstream reach. Halon 1211 is discharge from an extinguisher in

a clear liquid stream, giving it greater reach than a gaseousagent; however, the stream may be affected by wind whenoperated outside.

Figure 6.9 : A typical hand-carried halon extinguisher.


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Halon 1301 Halon 1301 is normally not used by itself in portable fireextinguishers because the agent is discharge as a nearlyinvisible gas that is highly susceptible to being affected bywind. In a confined space, such as a computer room, theagents volatility allows it to disperse faster than Halon 1211.For this reason, and because it is effective at a lowerconcentration than Halon 1211, Halon 1301 is agent of choicein most total-folding system using halogenated agents (Figure7.0).

Figure 7.0 : A Halon 1301 tank in a fixed system

Carbon Dioxide Extinguishers

Carbon dioxide is rated for class B and C fires only. It does not conduct electricity and hastwo significant advantages over dry chemical agents: it is not corrosive and it does not leaveany residues. Carbon dioxide also has several limitations and disadvantages (Figure 7.1).These inculade:

Weight Carbon dioxide extinguishers are heaver than similarly ratedextinguisher that use other extinguishing agents.

Range Carbon dioxide extinguishers have a short discharge range, whichrequires the operator to be close to the fire, increasing the risk ofpersonal injury.

Weather Carbon dioxide does not perform well at temperatures below 0F(- 18C) or in windy or drafty condition, because it dissipates before it reachesthe fire.

Confined spaces When use in confined areas, carbon dioxide dilutes theoxygen in the air. If enough oxygen is displaced, people in the space canbegin to suffocate.

Suitability Carbon dioxide extinguishers are not suitable for use on firesinvolving pressurized fuel or on cooking grease fires.

Figure 7.1 : Carbon Dioxide Extinguishers


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Dry Chemical Extinguishers

The terms dry chemical and dry powder are often incorrectly used interchangeably. Dry

chemical agents are for use on Class A,B,C fires and/or Class B,C fires. Dry powder agentsare for Class D fires only. Dry chemical extinguishers are among the most comman portablefire extinguishers in use today. There are two basic types of dry chemical extinguishers: (1)regular B:C-rated and (2) multipurpose and A:B:C-rated (see Extinguisher Rating System

section) (Figure 7.2). Unless specifically noted in this section, the characteristics andoperation of both types are exactly the same. The following are commonly used drychemical.

Sodium bicarbonate

Potassium bicarbonate

Urea-potassium bicarbonate

Potassium Chloride

Monoammonium phosphate

Figure 7.2 : A handcarried dry chemical fire extinguisherrated for Classes A, B, C fires.

QUALITIES AND EFFECTIVENESS ON THE CLASSES OF FIRE

Water Extinguishers

Water is an efficient, plentiful, and inexpensive extinguishing agent. When water isapplied to a fire, it quickly converts from liquid into steam, absorbing great quantities of heatin the process. As the heat is removed from the combustion process, the fuel cools below itsignition temperature and the fire stops burning.

Water is an excellent extinguishing agent for Class A fires. Many Class A fuels willabsorb liquid water, which further lowers the temperature of the fuel. This also preventsrekindling. Water is much less effective extinguishing agent for other fire classes.

Dry Chemical Extinguishers

Dry chemical extinguishers contain a variety of chemical extinguishing agents ingranular form. Hand-held dry chemical extinguishers are available with capacities rangingfrom I to 30 lbs of agent. Wheeled fire extinguishers are available with capacities up to 350

lbs of agent. Ordinary dry chemical models can be used to extinguish Class.B and C fires.Multipurpose dry chemical models are rated for use on Class A, B, and C fires.


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Dry Powder Fire Extinguishers

Dry powder fire extinguishersusing sodium chloride based agents are available with30 lb capacity in either stored-pressure or cylinder!cartridge models. Wheeled models areavailable with 150 lb and 350 lb capacities. Dry powder extinguishers have adjustablenozzles that allow the operator to vary the flow of the extinguishing agent. When the nozzleis fully opened, the hand-held models have a range of 6' to S'. Extension wand applicators

are available to direct the discharge from a more distant position.

Basic Steps of Fire Extinguisher Operation

Activating a fire extinguisher to apply the extinguishing agent is a single operation infour steps. The P-A-S-S acronym is a helpful way to remember these steps:

Pull the safety pin.

Aim the nozzle at the base of the flames.

Squeeze the trigger to discharge the agent.

Sweep the nozzle across the base of the flames.Most fire extinguishers have very simple operation systems. Practice discharging

different types of extinguishers in training situations to build confidence in your ability to usethem properly and effectively.

Follow the steps in ( ~ Skill Drill 7-2 )to operate a carbon dioxide extinguisher:

1. Size up the fire to determine what is burning, if there is energized electricalequipment involved or nearby, and if there are any other hazards present. Select theproper extinguisher.

2. Be sure the rating of the extinguisher matches the size of fire. If the fire is too largefor a portable fire extinguisher, back away until other suppression methodsare available. If possible, close off the area where the fire is located to limit the

spread of smoke and fire.

3. Check the pressure gauge on the extinguisher to ensure that it is properly charged.Remember, carbon dioxide fire extinguishers do not have pressure gauges.

4. Pull the pin on the handle. (Step 1)

5. Remove the horn or nozzle from the secured position on the extinguisher and aim inthe direction of your approach. (Step 2)

6. Give the trigger a quick squeeze to ensure that the extinguisher is operational andthe agent discharges properly. (Step 3)

7. Approach the fire with an exit to your back. Never let the fire get between you and theexit. Always have a safe exit path in case you have to evacuate. (Step 4)

8. Aim the nozzle of the fire extinguisher at the base of the fire and squeeze the trigger.(Step 5)

9. Sweep the extinguishing agent from side to side, continuing to aim at the base of theflames. Continue to use the extinguisher until the fire is out or the extinguisher isempty. (Step 6)


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10. If the extinguisher empties before the fire is completely suppressed, back away to asafe location and wait for assistance. If possible, close off the area where the fire isloc;ted to limit the spread of the fire until assistance arrives.

11. Back away from the fire. Never turn.your back on the fire. Be prepared in case itre-ignites.

12. Overhaul the fire to ensure that it is completely extinguished. Have additional fireextinguishers or a hose line available in case the fire flares up again. (Step 7)

Follow the steps of (~ Skill Drill 7-3)to attack a Class A fire with a stored-pressure water-type fire extinguisher.

1. Begin to attack the fire from a safe distance to take advantage of the reach of thestream. (Step 1)

2. Aim the stream directly at the base of the flames.

3. Sweep the nozzle back and forth, moving closer as the fire goes out. (Step 2)

4. After the flames are out, position your finger in front of the nozzle to create a sprayand soak the fuel. (Step 3)

5. If the fire is deep-seated (burning below the surface, as in a tightly packed trashbarrel or a brush pile), break the fuel apart with a stick or long-handled tool.Apply the extinguishing agent to any smoldering, smoking, or glowing surfaces.(Step 4)

6. Apply additional water spray to prevent the fire from re-igniting. (Step 5)

Follow the steps of ( Skill Drill 7-4 )to attack a Class A fire with a multipurpose drychemical fire extinguisher.

1. Begin to attack the fire from a safe distance taking advantage of the reach of the drychemical discharge stream.

2. Aim the stream directly at the base of the flames.

3. Sweep the nozzle back and forth, moving closer as the fire is extinguished.

4. After the flames are out, apply additional agent in short bursts to ensure that all hotsurfaces are coated with dry chemical.

5. If the fire is deep-seated (burning below the surface, as in a tightly packed trashbarrel or a brush pile), break the fuel apart with a stick or long-handled tool.Apply additional extinguishing agent to any smoldering, smoking, or glowingsurfaces.

6. Watch for indications of re-ignition and apply additional agent in short bursts asrequired. If necessary, use a fine water spray to soak the fuel.

Follow 'the steps in ( ~ Skill Drill 7-5)to attack a Class B flammable liquid spill or pool firewith a dry chemical extinguisher.

1. Check the pressure gauge to ensure that it is properly charged (Step 1) and pull thepin on the handle. (Step 2)


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2. Begin fighting the fire from a safe distance, as specified on the extinguisher's label.(Step 3)

3. Do not aim the initial discharge directly into the liquid from close range. The high-velocity stream of extinguishing agent could splash and spread the burning fuel.(Step 4)

4. Discharge the stream at the base of the flame, starting at the near edge of the fireand working toward the back (Step 5)

5. Sweep the nozzle back and forth across the surface of the flammable liquid. (Step 6)

6. After the flames are extinguished, watch for indications of re-igmtion and be preparedto apply additional agent. Look for hot or smoldering objects that could provide asource of re-ignition. (Step 7)

Follow the steps in ( ~ Skill Drill 7-6)to attack a Class B flammable liquid spill or pool firewith a stored-pressure fire extinguisher containing AFFF or FFFP extinguishing agent.

1. Begin fighting the fire from a safe distance, as specified on the extinguisher's label.(Step 1)

2. Aim the discharge stream high over the top of the fire.

3. Aiming directly into the liquid could cause the burning fuel to splash and spread thefire. (Step 2)

4. Discharge the stream in an arc over the top of the fire, so that the foam drops gentlyonto the surface of the burning liquid. Lobthe foam to create a blanket that floats onthe surface. (Step 3)

5. Slowly sweep the stream back and forth above the flammable liquid to widen thefoam blanket. Use the stream to carefully push the foam blanket toward theback of the liquid surface.

6. If the fire is a spill on the ground, aim the stream at the ground in front of the fire andlet the foam bounce onto the front part of the fire. Let the foam blanket flow acrossthe surface of the burning liquid.

7. After the flames are extinguished, continue to apply agent until the surface of theflammable liquid is fully covered by a foam blanket. Look for hot or smolderingobjects that could re-ignite the liquid and apply the agent directly on them. (Step 4)

8. Apply additional agent as needed to maintain the foam blanket and control any re-ignition. (Step 5)

Inspection

According to NFPA 10, an inspection is a "quick check" to verify that a fireextinguisher is available and ready for immediate use. Fire extinguishers on fire apparatusshould be inspected as part of the regular equipment checks mandated by your department.The fire fighter charged with inspecting the extinguishers should:

Ensure that tamper seals are intact.

Determine fullness by weighing or "hefting" the extinguisher.

Examine all parts for signs of physical damage,corrosion, or leakage.


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Check the pressure gauge to be sure it is in the operable range.

Ensure that the extinguisher is properly identified by type and rating.

Shake dry chemical extinguishers to mix or redistribute the agent.

Check the nozzle for damage or obstruction by foreign objects.

If an inspection reveals any problems, the extinguisher should be removed fromservice until the required maintenance procedures are performed. Spare

extinguishers should be used until the problem is corrected.

CONCLUSION

Fire extinguishers can be used as initial response tools or to fight fires in specialsituations. Firefighters must know how to use fire extinguishers and to teach the public howto use them. Part of that knowledge includes classifying fires by their fuels, especiallyordinary combustibles, flammable liquids and gases, and energized electrical equipment.Knowing the classes of fire is the first step toward choosing the right extinguisher and thecorrect size. The four-step process for using an extinguisher is PASS: pull, aim, squeeze,and sweep.


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Portable Fire Extiguishers

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