Chapter 7: Portable Fire Extinguishers

Dry Powder

-Extinguishing agent suitable for use on combustible metal fires.

Wet Chemical System

-Extinguishing system that uses a wet-chemical solution as the primary extinguishing agent; usually installed in range hoods and associated ducting where grease may accumulate.

Dry Chemical

-Extinguishing system that uses dry chemical as the primary extinguishing agent; often used to protect areas containing volatile flammable liquids.

Air-Aspirating Foam Nozzle

-Foam nozzle especially designed to provide the aeration required to make the highest quality foam possible; most effective appliance for the generation of low-expansion foam.

Water-Mist

-In the fire service, water mist is associated with a fire extinguisher capable of atomizing water through a special applicator. -Water-mist fire extinguishers use distilled water, while back-pump type water-mist extinguishers use ordinary water.

Class B Fires

-Involve flammable and combustible liquids and gases, such as alcohol, gasoline, lubricating oils, and liquefied petroleum gas. -These fires can be extinguished with CO2, dry chemical and foam agents.

Class A Fires

-Involve ordinary combustibles such as textiles, paper, plastics, rubber and wood. -These can be easily extinguished with water, water-based agents such as foam, or dry chemicals.

Handling

-Never drop or throw a portable fire extinguisher. -Depending on the size and weight of the extinguisher, carry it diagonally across the body with one hand on the handle and the other on the bottom edge. -Do not remove the safety pin until you are ready to use the extinguisher. -When using multiple extinguishers at an incident or training, lay empty fire extinguishers on their sides after use. -This signals other firefighters that the extinguisher is empty and reduces the chance of someone approaching a fire with an empty unit.

Classifications

-Portable fire extinguishers are classified by the type of fire they are designed to extinguish. -The five classes of fire extinguishers match the five classes of fire: Class A, B, C, D, and K.

Fire Extinguisher

-Portable fire fighting device designed to combat incipient fires.

Saponification

-A phenomenon that occurs when mixtures of alkaline based chemicals and certain cooking oils come into contact resulting in the formation of a soapy film.

Extinguishing Agent

-Any substance used for the purpose of controlling or extinguishing a fire.

Water-Mist Stored-Pressure Extinguisher

-Use deionized water as the agent and nozzles that produce a fine spray instead of a solid stream -Because it is the impurities in water that make it electrically conductive, the deionized water also makes these Class A extinguishers safe to use on energized electrical equipment (Class C) -The fine spray enhances the cooling and soaking characteristics of the water and reduces scattering of the burning materials

Deionized Water

-Water from which ionic salts, minerals, and impurities have been removed by ion-exchange.

Corrosive

-capable of causing corrosion by gradually eroding, Rusting, or destroying a material

13. What type of portable fire extinguisher may produce a cloud that reduces visibility when discharged? (349) A. Dry chemical B. Pump-type water C. Aqueous film forming foam D. Wet chemical stored-pressure

A

14. What type of portable fire extinguisher may be applied with either an extinguisher or a scoop? (350) A. Dry powder B. Dry chemical C. Pump-type water D. Wet chemical stored-pressure

A

23. Signal to others that a portable fire extinguisher is empty by: (356) A. laying it on its side. B. marking it with a tag. C. standing it straight up. D. covering the hose with a blanket.

A

26. Do not remove the safety pin on a portable fire extinguisher until: (358) A. ready to use the extinguisher. B. the fire appears to be dying out. C. ordered to by the commanding officer. D. you are 10 feet (3.04 meters) from the fire.

A

Extinguishing Agent Characteristics

Agent/Primary Method/Secondary Method -Water/Cooling/Oxygen Depletion -Carbon Dioxide/Oxygen Depletion/Cooling -Foam/Oxygen Depletion/Vapor Suppression -Clean Agent/Chain Inhibition/Cooling -Dry Chemical/Chain Inhibition/Oxygen Depletion -Wet Chemical/Oxygen Depletion/Vapor Suppression -Dry Powder/Oxygen Depletion/Heat Transfer Cooling

15. What portable fire extinguisher rating is based on the approximate square foot (square meter) area of flammable liquid a nonexpert operator can extinguish? (352) A. Class A rating B. Class B rating C. Class K rating D. Multiple markings

B

18. Which statement BEST describes portable fire extinguisher selection? (354) A. Extinguisher ratings do not impact selection. B. The correct extinguisher will minimize risk to life and property. C. The correct extinguisher will always require an expert operator. D. All types of extinguishers can be selected regardless of the situation

B

6. What expelling mechanism works when the operator physically applies pressure to a pump that increases pressure within the container? (343) A. Scoop B. Manual pump C. Stored pressure D. Pressure cartridge

B

9. What type of portable fire extinguisher is intended for use on Class K fires? (346) A. Clean agent B. Pump-type water C. Aqueous film forming foam D. Wet chemical stored-pressure

D

Inspection, are, and Maintenance

-All fire departments have standard operating procedures (SOPs) for the inspection, care, and maintenance of their portable fire extinguishers. -These procedures are based on NFPA 10, Standard for Portable Fire Extinguishers. -Extinguishers owned by private companies, organizations, and individuals are regulated by locally adopted codes and standards. -NFPA 10 and most fire and life safety codes require that portable fire extinguishers be inspected at least once a year to ensure that they are accessible and operable. -Your departments SOPs establish the inspection requirements for its portable extinguishers. -Typically, inspections are performed at the beginning of each shift or at least weekly.

Stored Pressure

-Compressed air or inert gas within the container forces the agent out a nozzle at the end of a hose when the operator presses the handle.

Clean Agent Extingusihers

-Developed to replace Halogenated Extinguishing Agents -Extremely effective for extinguishing fires in computer rooms, aircraft engines, and areas that contained materials that could easily be damaged by water or dry chemical agents -Discharged as a rapidly evaporating liquid that leaves no residue -Effectively cool and smother fires in Class A and Class B fuels, and the agents are nonconductive so they can be used on energized electrical (Class C) fires

Class C Fires

-Involve energized electrical equipment -Because water and water-based agents will conduct electrical current, they cannot be used on Class C fires until the electrical energy has been eliminated -Class C extinguishing agents will not conduct electricity making them suitable for electrical fires -Once the power supply has been turned off or disconnected, the fire can be treated as a Class A or B fire

Class C

-No extinguishing capability tests. -Tests only determine nonconductivity.

Class D

-No numerical ratings. -Tested for reactions, toxicity, and metal burnout time.

Class K

-No numerical ratings. -Tested to ensure effectiveness against 2.25 square feet (0.2 meter2 of light cooking oil in a deep fat fryer.

Types of Portable Fire Extinguishers

-Organized by the type of fire they will extinguish, by the type of extinguishing agent, and by the method used to expel the contents -Extinguishing Agents use one of the following to extinguish fires: >Smothering - excluding oxygen from the burning process >Cooling - reducing the burning material below its ignition temperature >Chain Breaking - interrupting the chemical chain reaction in the burning process >Saponification - forming an oxygen-excluding soapy foam surface

1. Portable fire extinguishers should be chosen based on the: (340) A. heat of the fire. B. type of fuel that is burning. C. amount of agent required to extinguish the fire. D. distance required between the extinguisher and the fire.

B

2. What classification of portable fire extinguisher is used for fires that involve combustible liquids and gases? (341) A. Class A B. Class B C. Class D D. Class K

B

25. During inspection, if a portable fire extinguisher is found deficient in weight by ___ percent it should be removed from service and replaced. (357) A. 5 B. 8 C. 10 D. 12

C

27. How often should portable fire extinguishers be removed from service for maintenance? (358) A. Monthly B. Bi-monthly C. Annually D. Bi-annually

C

3. What classification of portable fire extinguisher is used for fires that involve combustible metals and alloys? (341) A. Class A B. Class B C. Class D D. Class K

C

21. The P in the PASS acronym stands for: (355) A. squeeze handles. B. aim nozzle at base of fire. C. sweep nozzle back and forth. D. pull pin by breaking wire or seal.

D

Using a Wheeled Extinguisher

-Carbon dioxide wheeled units are similar to the handheld units, except that they are considerably larger -- usually in 50-to 100-pound (23 Kg to 45 Kg) capacities. -They are most commonly used in airports and industrial facilities. -The principle of operation is the same as in the smaller handheld units, except after being wheeled to the fire the hose must be deployed or unwound before use.

Halogenated Extinguishing Agents

-Chemical compounds (halogenated hydrocarbons) that contain carbon plus one or more elements from the halogen series. -Halon 1301 and Halon 1211 are most commonly used as extinguishing agents for Class B and Class C fires. -Also known as Halogenated Hydrocarbons.

24. NFPA® 10 requires inspection of portable fire extinguishers at least: (357) A. after every use. B. every three months. C. once every six months. D. once a year.

D

4. What classification of portable fire extinguisher is used on fires that involve combustible cooking oils? (342) A. Class A B. Class B C. Class D D. Class K

D

Stored-Pressure Water Extinguishers

-Also called air-pressurized water (APW) extinguishers or pressurized water extinguishers -Used for all types of Class A fires -Water is stored in a tank along with compressed air or nitrogen -When the operating valve is activated, the stored pressure forces up the siphon tube and out through the hose

Cleaning

-Clean the extinguisher after each use or periodically. -Use warm water and soap to remove dirt, grease, and other foreign material. -Avoid using solvents that might damage plastic parts, like the gauge face. -Remove any corrosion with steel wool or sand paper.

Pressure Cartridge

-Compressed inert gas is contained in a separate cartridge on the side of the container. -When the operator punctures the cartridge, the expellant enters the container forcing the agent out a nozzle on the end of a hose.

Operating a Dry Chemical Extinguisher

-Dry chemical extinguishers are the most common portable fire extinguishers in use today. -Dry chemical extinguishers are often rated for more than one Class of fire. -Ordinary dry chemical extinguishers are for Class B and Class C fires. -Multipurpose dry chemical extinguishers are rated for Class A, B and C fires. -The operation of both types is basically the same. -There are two main types of designs for hand-held dry chemical extinguishers: >stored-pressure and >cartridge-operated.

Operating a Dry Powder Extinguisher

-Dry powder extinguishers are used to control and extinguish fires involving combustible metals (Class D fires). -Some agents are effective against several types of combustible metals; others are effective against only one type of metal. -Keep this in mind, because using the wrong agent on these fires can intensify the problem. -Dry powder agents may be applied with portable extinguishers or with a shovel or scoop. -The appropriate application technique for any given dry powder is described in the manufacturer's technical sales literature. -You should be thoroughly familiar with the information that applies to any agent carried on your apparatus.

Carbon Dioxide Extinguishers

-Found as both handheld and wheeled units -Most effective in extinguishing Class B and C fires -Discharged in the form of a gas, have limited reach, and can be dispersed by wind -Stored under its own pressure as a liquified gas ready for release at any time -Agent discharged through a plastic or rubber horn on the end of either a short hose or tube -Gaseous discharge is accompanied by dry ice crystals, which changes from a solid to a gas without becoming a liquid -When released, Carbon Dioxide gas displaces available oxygen and smothers the fire

Rating System

-In addition to the classification represented by the letter, Class A and Class B extinguishers are also rated by a number that shows performance capability. -The higher the numbered rating, the greater the extinguishing power. +The classification and ratings must be clearly marked on the faceplate of all extinguishers.

Aqueous Film Forming Foam (AFFF) Extinguishers

-Intended for Class B fires -Different from stored-pressure water extinguishers in two ways: 1) the AFFF extinguisher tank contains a specified amount of AFFF concentrate mixed with the water to produce a foam solution 2) it has an air-aspirating foam nozzle that aerates the foam solution, producing a better quality foam than the standard extinguisher nozzle provides -The solution is expelled using compressed air or nitrogen stored in the tank with the solution -The resulting finished foam floats on the surface of fuels that are lighter than water -The vapor seal created by the film of water extinguishes the flame and prevents reignition -Should be allowed to gently rain down on the fuel surface or deflect off a nearby object or surface -*Not suitable for Class C, D, or K fuels*

Wet Chemical Stored-Pressure Extinguishers

-Intended for use on Class K fires involving cooking fats, greases, and vegetable and animal oils in commercial kitchens -Contain a special potassium-based, low pH agent formulated to operate on the principle of saponification in which the agent combines with the oils to create a soapy foam surface over cooking appliance

Pump-Type Water Extinguishers

-Intended primarily for use on ground cover fires although, they may also be used for small Class A fires -Designed to be worn on the back with a manually operated trombone-style slide pump -The nozzle produces a straight stream, fog, or water-mist pattern

Class K Fires

-Involve combustible cooking oils such as vegetable or animal fat oils that burn at extremely high temperatures. -Wet Chemicals are used in the extinguishing systems and portable extinguishers on these fires.

Class D Fires

-Involve combustible metals such as magnesium, lithium, potassium, or sodium -Some common uses of magnesium are in wheels and transmission components for automobiles and even some metal box springs in beds -These types of fires can be identified by the bright white emissions during the combustion process -The use of water or water-based agents on Class D fires will cause the fire to react violently, emit bits of molten metal, and possibly injure firefighters close by -Dry powder extinguishers work best on these types of fires -*Do not use dry chemical agents on Class D fires (will react violently with burning metals)*

Operating a Carbon Dioxide Extinguisher

-Portable carbon dioxide (CO2) extinguishers are most effective in extinguishing Class B and Class C fires. -Because their discharge is in the form of a gas, they have a limited reach and the gas can be dispersed by wind. -The carbon dioxide is stored under its own pressure as a liquefied gas and discharges through a plastic or rubber horn on the end of either a short hose or tube. -The discharge is usually accompanied by dry ice crystals or carbon dioxide "snow." -Portable CO2 extinguishers may be hand-held or wheeled units.

Selection Factors

-Portable extinguishers are chosen when they can extinguish the fire effectively and minimize the risk to life and property. -Normally, your supervisor will decide when fighting a fire with portable extinguishers is best and which extinguishers you should use. -However, if you must make the decision on your own, consider the following factors: >Classification of the burning fuel >Rating of the extinguisher >Hazards to be protected >Size and intensity of the fire >Atmospheric conditions >Availability of trained personnel >Ease of handling extinguisher >Any life hazard or operational concerns -Because of their corrosive particulate residue, do not select dry chemical extinguishers for use in areas with highly sensitive computer equipment. -The residue could do more damage than the fire. In these areas, clean agent or carbon dioxide extinguishers are better choices.

Identification Systems

-Portable fire extinguishers are identified in two ways. -One system uses geometric shapes of specific colors with the class letter shown within the shape. -The second system, currently recommended in NFPA® 10, uses pictographs to make the selection of the most appropriate fire extinguishers easier. -A pictograph with a red line through it indicates the extinguisher should NOT be used on that type of fire.

Maintenance

-Portable fire extinguishers must be removed from service once a year for maintenance, which includes a thorough inspection and disassembly of the unit. -Owners should keep records of maintenance and inspections. -Fire service inspectors review these records during their visit. -Units that operate under pressure must be hydrostatically tested periodically; results of the hydrostatic test are affixed to the extinguisher shell. -Every six years, dry chemical portable extinguishers should be emptied and refilled with dry chemical agent. -NFPA 10 provides more information about testing and documentation requirements.

Wheeled Units

-Rated for Class A, B, and C fires based on the chemical in the unit -Extinguishing agent is kept in one tank and the pressurizing gas is stored in a separate cylinder -Operator should be prepared for a significant nozzle reaction when opened

Class A

-Rated with numbers, 1-A through 40-A, based on the amount of extinguishing agent and the duration and range of the discharge used in extinguishing test fires. >1-A = 1 ¼ gallons (5 L) of water. >2-A = 2 ½ gallons (10 L) of water.

Class B

-Rated with numbers, 1-B through 640-B, based on the square foot (or meter) area of a flammable liquid fire a non-expert user can extinguish. >1-B = 1 square foot area (0.09m2) of liquid fire. >640-B = 640 square feet (58m2) of liquid fire.

Limitations of Portable Extinguishers

-Remember that portable fire extinguishers are not sufficient to control a structure fire. -They are designed to be used only for attacking small fires in the incipient or early growth stage. -Whenever using a portable extinguisher, you must be prepared for the worst possible scenario. -Wear full PPE including respiratory protection when entering the hazard zone. -Be aware of the clues indicating the stage of the fire. -Follow local SOPs for establishing a water supply during initial attack. -Back away from the fire if you feel outgunned.

Storage

-Store the extinguisher securely in its mounting bracket. -Do not store or stack items in front of wall-mounted extinguishers. -Shake dry chemical extinguishers monthly to loosen the agent and prevent it from settling.

Handheld Units

-Stored Pressure: >constant pressure of about 200 psi maintained in the agent storage tank -Cartridge Operated: >employ a pressure cartridge connected to agent tank >agent tank is not pressurized until a plunger is pushed to release the gas from the cartridge -Both use either nitrogen or carbon dioxide as the pressurizing gas

Manual Pump

-The operator physically applies pressure to a pump that increases pressure within the container, forcing the agent out a nozzle at the end of a hose.

Dry Chemical Extinguishers

-Used for Class A-B-C fires and/or Class B-C fires -Two basic types of extinguishers: 1) Regular B:C rated 2) Multipurpose and A:B:C rated -Nontoxic and generally considered safe to use -Some dry chemicals are compatible with foam -On Class A fires, the discharge should be directed at whatever is burning in order to cover it with chemical -Should be applied intermittently as needed on any smoldering areas

Dry Powder Extinguishers

-Used for extinguishing Class D fires -No single agent will control or extinguish fires in all combustible metals -Can be applied with portable extinguishers or shovels/scoops -Must be applied in sufficient depth to completely cover the burning area in order to create a smothering blanket -Should be applied gently to avoid breaking any crust that may form over a burning metal -If the crust is broken, the fire may flare and expose more uninvolved material to combustion

10. The resulting foam from an aqueous film forming foam (AFFF) extinguisher will ___ fuels lighter than air. (346) A. mix in with B. float on the surface of C. sink below the surface of D. cause a chemical reaction with

B

19. Once the proper extinguisher is selected, you must perform a visual inspection to ensure the extinguisher: (354) A. has no external marks. B. is charged and operable. C. feels as though it contains agent. D. has a long enough hose to reach the fire.

B

20. Once the proper extinguisher is selected, you must check to ensure the pressure gauge: (354) A. is not clouded over. B. is in the operable range. C. has been properly inspected. D. records the last maintenance performed.

B

5. Which method of extinguishing works by excluding oxygen from the burning process? (342) A. Cooling B. Smothering C. Saponification D. Chain breaking

B

7. What type of portable fire extinguisher is intended primarily for ground cover fires? (345) A. Clean agent B. Pump-type water C. Aqueous film forming foam D. Wet chemical stored-pressure

B

11. What application method is used with an aqueous film forming foam (AFFF) extinguisher in order to prevent disturbing the fuel? (346) A. Apply foam directly to fuel surface B. Apply foam in conjunction with dry ice crystals C. Allow foam to gently rain down onto fuel surface D. Allow foam to rest before applying to fuel surface

C

12. What type of portable fire extinguisher is discharged in the form of gas and works on Class B and Class C fires? (348) A. Clean agent B. Pump-type water C. Carbon dioxide (CO2) D. Wet chemical stored-pressure

C

22. Which of the following statements BEST describes how to prevent scattering of lightweight fuels? (356) A. Wind may be used to allow the agent to reach the fuel surface. B. First allow fuel to burn off vapors before applying agent to the fuel surface. C. Apply the agent from point where it reaches, but does not disturb, the fuel surface. D. Use two extinguishers, alternating application patterns, to apply agent to the fuel surface.

C

16. What portable fire extinguisher rating considers both the toxicity of the extinguishing agent and the toxicity of fumes produced when the agent is applied? (352) A. Class A rating B. Class B rating C. Class C rating D. Class D rating

D

8. What type of portable fire extinguisher uses air stored in the tank to force water up a siphon tube when operated? (346) A. Clean agent B. Pump-type water C. Carbon dioxide (CO2) D. Stored-pressure water

D

PASS

P - Pull the pin breaking the thin wire or plastic seal A - Aim the nozzle at the base of fire S - Squeeze the handles together to release the agent S - Sweep the nozzle back and forth to cover the burning material

17. On a multiple marking extinguisher the ratings for each class are: (353) A. directly related to the others. B. only identified by pictographs. C. separate, they do not affect each other. D. indicators that firefighters should not use them.

c