Chapter 7: Portable Fire Extinguishers

What are components of a fire extinguisher inspection?

• Check to ensure that the extinguisher is in its proper location and that it is accessible. • Inspect the discharge nozzle or horn for obstructions. • Check hose for cracks and dirt or grease accumulations. • Inspect the extinguisher container shell for any physical damage. • Check to see if the operating instructions on the extinguisher nameplate are legible. • Check the locking pin and tamper seal to ensure that the extinguisher has not been discharged or tampered with. • Determine if the extinguisher is full of agent and fully pressurized by checking the pressure gauge, weighing the extinguisher, or inspecting the agent level. If an extinguisher is found to be deficient in weight by 10 percent, it should be removed from service and replaced. • Check the inspection tag for the date of the previous inspection, maintenance, or recharging

What are some guidelines for handling and storing portable fire extinguishers?

• 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. • Store the extinguisher securely in its apparatus or facility mounting bracket. • Lay empty extinguishers on their sides to indicate that they are out of service. • 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.

How are Class C Extinguishers identified?

A blue circle

How are Class D Extinguishers identified?

A yellow star

What should a firefighter do after extinguisher use?

Always recharge or refill fire extinguishers regardless of the amount of agent used. Recharging must be performed by trained personnel in accordance with the manu- facturer's instructions.

How are pressurized extinguishers tested?

Because pressurized portable fire extinguishers operate under internal pressure, they must be hydrostatically tested periodically. NFPA® 10 describes procedures for the hydrostatic testing of extinguisher cylinders as required by both the U.S. Department of Transportation and Transport Canada. The test results must be affixed to the extinguisher shell. The hydrostatic test results on high- and low-pressure cylinders are recorded differently. Maintenance personnel should refer to NFPA® 10 for specific information on extinguisher testing and documentation.

What is a Class C fire?

Class C fires involve energized electrical equipment.

How and when should you clean extinguishers?

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 dam- age plastic parts like the gauge face. Remove any corrosion with steel wool or sand paper

What is the most common portable fire extinguisher?

Dry Chemical

Who should repair or refill portable fire extinguishers?

Only trained personnel should repair or refill portable fire extinguishers.

How often should extinguishers be maintenance?

Portable fire extinguishers should be removed from service for annual maintenance.

Manual Pump Extinguisher

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.

What has to be done to an extinguisher upon inspection?

This maintenance includes a thorough inspection and disassembly of the unit.

Where can fuels for Class K fires be found?

While most of these fuels are found in commercial and institutional kitchens and industrial cooking facilities, they can also be found in private homes.

What are Stored-Pressure Water Extinguishers used for?

all types of small Class A fires. They are often used for extinguishing confined hot spots during overhaul operations.

What is a disadvantage of Halon Extinguishers?

halogenated extinguishing agents also have a very damaging effect on the atmosphere's ozone layer.

How is the class B rating determined?

he rating is based on the approximate square foot (square meter) area of a flammable liquid fire that a nonexpert operator can extinguish using one full extinguisher. The nonexpert operator is expected to extinguish 1 square foot (0.09 m2) for each numerical rating or value of the extinguisher rating.

What determines the value of an extinguisher?

• Serviceability • Accessibility • Simplicity of operation

What are two types of dry chemical Extinguishers?

1. Regular B:C-rated 2. Multipurpose and A:B:C-rated (see Extinguisher Rating System section)

How are AFFF Extinguishers different from Stored-Pressure Extinguishers?

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 a standard extinguisher nozzle provide

What class fire do dry chemical agents extinguish?

Special dry powder extinguishing agents and application techniques have been developed to control and extinguish fires involving Class D combustible metals.

How should one apply a foam blanket when using an AFFF extinguisher?

To prevent the disturbance of the foam blanket when applying the foam, it should not be applied directly onto the fuel; instead, it should be allowed to either gently rain down onto the fuel surface or deflect off a nearby object or surface.

How does a Stored-Pressure Water Extinguisher work?

Water is stored in a tank along with either compressed air or nitrogen. A gauge located on the side of the valve assembly shows when the extinguisher is properly pressurized. When the operating valve is activated, the stored pressure forces water up the siphon tube and out through the hose.

What are the two basic designs of handheld dry chemical extinguishers?

cartridge- operated and stored-pressure.

What type of water and nozzle are utilized on a Water-Mist Stored-Pressure Extinguisher?

Deionized water The nozzle produces a fine spray

Why should the hose on wheeled dry chemical extinguishers be fully stretched out?

Once the agent storage tank and hose are charged, it can make removing the hose more difficult and the powder can sometimes clog in any sharp bends in the hose.

What is another type of extinguisher that was developed to replace Halon Extinguishers?

Pressurized with argon gas, Halotron extinguishers are approved by the U.S. Environmental Protection Agency (EPA).

What are the primary and secondary methods of Clean Agent as an extinguishing agent?

Primary: Chain Inhibition Secondary: Cooling

What are the primary and secondary methods of Dry Chemical as an extinguishing agent?

Primary: Chain Inhibition Secondary: Oxygen Depletion

What are the primary and secondary methods of water as an extinguishing agent?

Primary: Cooling Secondary: Oxygen depletion

What are the primary and secondary methods of Carbon Dioxide as an extinguishing agent?

Primary: Oxygen Depletion Secondary: Cooling

What are the primary and secondary methods of Dry Powder as an extinguishing agent?

Primary: Oxygen Depletion Secondary: Heat Transfer Cooling

What are the primary and secondary methods of Foam as an extinguishing agent?

Primary: Oxygen Depletion Secondary: Vapor Suppression

What are the primary and secondary methods of Wet Chemical as an extinguishing agent?

Primary: Oxygen Depletion Secondary: Vapor Suppression

How is the Class C rating described?

Because electricity does not burn, extinguishers for use on Class C fires receive that letter rating because Class C fires are essentially Class A or Class B fires involving energized electrical equipment.

What types of fires can Water-Mist Stored-Pressure Extinguishers?

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 also enhances the cooling and soaking characteristics of the water and reduces scattering of the burning materials.

What must firefighters be cautious around computer equipment related to fire extinguishment?

Because of their corrosive particulate residue, do not select dry chemical extinguishers for use in areas where highly sensitive computer equipment is located. The residue left afterward could potentially do more damage to the sensitive electronic equipment than the fire. In these particular areas, clean agent or carbon dioxide extinguishers are better choices.

What makes Class C fires more complex than Class A or B fires?

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.

What type of gas is used in both handheld dry-chemical extinguishers?

Both types of extinguishers use either nitrogen or carbon dioxide as the pressurizing gas.

What fires can CO2 Extinguishers extinguish?

CO2 extinguishers are most effective in extinguishing Class B and Class C fires.

What are characteristics of C02 fire extinguishers?

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. Wheeled units are most commonly used in airports and industrial facilities. After being wheeled to the fire, the hose (usually less than 15 feet [5 m] long) must be deployed or unwound from the unit before use.

How often must dry chemical extinguishers be changed if they are not used?

Every six years the dry chemical extinguishing agent should be emptied and the extinguisher refilled. This should be done in a controlled atmosphere to prevent the agent from spreading through the area.

Why would class A foam be added to a Stored-Pressure Water Extinguisher?

The addition of Class A foam concentrate serves as a wetting agent to improve the extinguishers effectiveness by aiding in extinguishing deep-seated fires, such as those in upholstered furniture or vehicle seats and wildland fires in densely matted vegetation.

What types of fire can Clean Agent Extinguishers be used on?

These agents 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 equipment (Class C) fires.

How do Wet Chemical Stored-Pressure Extinguishers operate?

These fire extinguishers 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 the cooking appliance.

What is a disadvantage of C02 Extinguishers?

Because their discharge is in the form of a gas, they have a limited reach and the gas can be dispersed by wind.

What is a Class B fire?

Class B fires involve flammable and combustible liquids and gases, such as alcohol, gasoline, lubricating oils, and liquefied petroleum gas (LPG).

What type of fire are Aqueous Film Forming Foam (AFFF) Extinguishers intended for?

Class B fires, and They are particularly useful in combating fires in or suppressing vapors from small liquid fuel spill

How are Class C fires extinguished?

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.

How are Class D fires extinguished?

Class D dry powder extinguishers work best on these types of fires; however, do not confuse dry powder extinguishers with dry chemical units used on Class A, B, and C fires. It is important to remember that dry chemical agents such as sodium and potassium bicarbonate will react violently with the burning metal if applied to a Class D fire.

What is a Class D fire?

Class D fires are those involving combustible metals and alloys such as lithium, magnesium, potassium, and sodium. These types of fires can be identified by the bright white emissions during the combustion process.

What are dry powder agents used for?

Class D fires only

What Models do dry powder extinguishers come in?

Class D portable fire extinguishers come in both handheld and wheeled models

What is a Class K fire?

Class K fires involve combustible cooking oils such as vegetable or animal fats and oils that burn at extremely high temperatures.

What class of fire are Wet Chemical Stored-Pressure Extinguishers intended for?

Class K fires involving cooking fats, greases, and vegetable and animal oils in commercial kitchens.

What must Class K fires be capable of?

Class K rated extinguishers must be capable of saponifying (converting the fatty ac- ids or fats to a soap or foam) vegetable oil, peanut oil, canola oil, and other oils with little or no fatty acids.

Why were clean agent extinguishers developed?

Clean agents have been developed to replace halogenated extinguishing agents.

Where are commercial Kitchens located?

Commercial and institutional kitchens may be located in schools, hospitals, cafeterias, restaurants, and catering establishments

Stored Pressure Extinguisher

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.

Pressure Cartridge Extinguisher

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

What are characteristics of Clean Agent Extinguishers?

Designed specifically as replacements for Halon 1211, clean agents are discharged as a rapidly evaporating liquid that leaves no residue. Clean agents include FE-36TM hexafluoropropane. hydrochlorofluorocarbon (HCCF), hydrofluorocarbon (HFC), perfluorocarbon (PFC), or fluoroidiocarbon (FIC)

What are characteristics of dry chemical?

During manufacture, dry chemical agents are mixed with small amounts of additives that make the agents moisture-resistant and prevent them from caking (drying or hardening into a mass). This process keeps the agents ready for use even after being stored for long periods, and it makes them free flowing.

What is an example of a 1-A rating conversion?

For a 1-A rating, 11⁄4 gallons (5 L) of water are required. A 2-A rating requires 21⁄2 gallons (10 L) or twice the 1-A capacity.

halogenated extinguishing agents

Halon is a generic term for halogenated hydrocarbons and is defined as a chemical compound that contains carbon plus one or more elements from the halogen series (fluorine, chlorine, bromine, or iodine). The two most common Halon extinguishing agents are Halon 1211 (bromochlorodifluoromethane) and Halon 1301 (bromotri- fluoromethane).

How/Where are Halons used as extinguishing agents?

Halons were extremely effective for extinguishing fires in computer rooms, aircraft engines, and areas that contained materials that could easily be dam- aged by water or dry chemical agents.

What chemicals associated with dry chemical extinguishers could deteriorate a foam blanket?

Monoammonium phosphate and some sodium bicarbonate agents will cause the foam blanket to deteriorate when applied in conjunction with or after foam to a Class B fire or spill.

Is there any one extinguishing agent that will extinguish any combustible metal?

No single extinguishing agent will control or extinguish fires in all combustible metals. Some agents are effective against fires in several metals; others are effective on fires in only one type of metal.

How should dry chemical extinguishers be used?

On Class A fires, the discharge should be directed at whatever is burning in or- der to cover it with chemical. When the flames have been knocked down, the agent should be applied intermittently as needed on any smoldering areas. Many dry chemical agents can be mildly corrosive to all surfaces.

How are Dry Chemical wheeled units operated?

Operating the wheeled dry chemical extinguisher is similar to operating the handheld, cartridge-type dry chemical extinguisher. The extinguishing agent is kept in one tank and the pressurizing gas is stored in a separate cylinder. When the extinguisher is in position at a fire, the hose should first be stretched out completely. The pressurizing gas should be introduced into the agent tank and allowed a few seconds to fully pressurize the tank before the nozzle is opened. Because of the size of the nozzle, the operator should be prepared for a significant nozzle reaction when it is opened. The agent is applied in the same manner as described for the handheld, cartridge-type dry chemical extinguishers.

What does PASS stand for in relation to fire extinguishers?

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

What does NFPA 10 pertain to?

Pictographs on to identify classes of extinguishers

What are Carbon Dioxide Extinguishers common forms?

Portable carbon dioxide (CO2) fire extinguishers are found as both handheld and wheeled units

What is the range for Class B ratings?

Portable fire extinguishers suitable for use on Class B fires are classified with numerical ratings ranging from 1-B through 640-B.

Where can combustible metals be found?

Some common uses of magnesium are in wheels and transmission components for automobiles and even some metal box springs in beds.

Are all dry powder agents applied the same?

Some powdered agents can be applied with portable extinguishers, but others must be applied with either a shovel or a scoop.

How do Wet chemical agents suppress a fire?

Wet chemical agents containing an alkaline mixture, such as potassium acetate, potassium carbonate, or potassium citrate, work by suppressing the vapors and smothering the fire.

How can Class K fires be extinguished?

Wet chemical systems and portable fire extinguishers are used to control and extinguish Class K fires.

How do dry chemical wheeled units compare to dry chemical handheld units?

Wheeled units are larger

What must you check immediately before use of a portable fire extinguisher?

• External condition — No apparent damage • Hose/nozzle — In place • Weight — Feels as though it contains agent • Pressure gauge (if available) — In operable range

What are some common types of extinguishers?

• Pump-Type Water Extinguishers • Stored-Pressure Water Extinguishers • Water-Mist Stored-Pressure Extinguishers • Wet Chemical Stored-Pressure Extinguishers • Aqueous Film Forming Foam (AFFF) Extinguishers • Clean Agent Extinguishers • Carbon Dioxide (CO2) Extinguishers • Dry Chemical Extinguishers • Dry Powder Extinguishers

What are methods of extinguishing a fire?

• 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

What are some commonly used dry chemicals

• Sodium bicarbonate • Potassium bicarbonate • Urea-potassium bicarbonate • Potassium chloride . • Monoammonium phosphate

How are Class K Extinguishers identified?

A black hexagon

How are Class A Extinguishers identified?

A green triangle

How are Class B Extinguishers identified?

A red square

What can extinguish Class B fires?

Agents used to extinguish special hazard Class B fires are carbon dioxide (CO2), dry chemical, and Class B foam.

What is another name for Stored-Pressure Water Extinguishers?

Air-Pressurized Water Extinguishers (APW)

What is the minimum criteria for a Class K rating?

Any of these agents capable of extinguishing a fire from a deep fryer using these light oils with a surface area of 2.25 square feet (0.2 m2) meet the minimum criteria for Class K rating.

How does a CO2 Extinguisher operate?

Carbon dioxide is stored under its own pressure as a liquefied gas ready for release at any time. The agent is discharged through a plastic or rubber horn on the end of either a short hose or tube. The gaseous discharge is usually accompanied by dry ice crystals or carbon dioxide "snow." Shortly after discharge, this snow changes from a solid to a gas without becoming a liquid. When released, the carbon dioxide gas dis- places available oxygen and smothers the fire. Even though CO2 discharges at subzero temperatures, it has little if any cooling effect on fires. Carbon dioxide produces no vapor-suppressing film on the surface of the fuel; therefore, reignition is always a danger.

What are some characteristics of cartridge-operated handheld dry chemical extinguishers?

Cartridge-operated extinguishers employ a pressure cartridge connected to the agent tank. The agent tank is not pressurized until a plunger is pushed to release the gas from the cartridge. Cartridge-operated extinguishers use a carbon dioxide cartridge unless the extinguisher is going to be subjected to freezing temperatures; in such cases, a dry nitrogen cartridge is used.

What is a Class A fire?

Class A fires involve ordinary combustibles such as textiles, paper, plastics, rubber, and wood.

How does class A foam aid in extinguishing a fire?

Class A foam concentrate in water enhances its effectiveness by reducing the surface tension of water, allowing the water to quickly penetrate the surface.

What are the rating for Class A?

Class A portable fire extinguishers are rated from 1-A through 40-A.

What are dry chemical agents used for?

Class A-B-C fires and/or Class B-C fires;

How are Class D ratings established?

Test fires for establishing Class D ratings vary with the type of combustible metal being tested. The following factors are considered during each test: • Reactions between the metal and the agent • Toxicity of the agent • Toxicity of the fumes produced and the products of combustion • Time to allow metal to burn completely without fire suppression compared to the time to extinguish the fire using the extinguish When an extinguishing agent is determined to be safe and effective for use on a combustible metal, the application instructions are included on the faceplate of the extinguisher, although no numerical rating is given. Class D agents cannot be given a rating for use on other classes of fire.

How is the Class A Rating determined?

The Class A rating of water extinguishers is primarily based on the amount of extinguishing agent and the duration and range of the discharge used in extinguishing test fires.

What are Class C rating designed for?

The extinguishing agent is tested for electrical nonconductivity. The Class C rating confirms that the extinguishing agent will not conduct electricity.

What are some characteristics of stored-pressure handheld dry chemical extinguishers?

The stored-pressure type is similar in design to the air-pressurized water extinguisher. A constant pressure of about 200 psi (1 400 kPa) is maintained in the agent storage tank.

What are common examples of multiple markings?

The three most common combinations are Class A-B-C, Class A-B, and Class B-C. Each rating is independent of each other.

How do AFFF solutions operate?

The water/AFFF 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. T

How is the class C rating determined?

There are not any fire extinguishing capability tests specifically conducted for Class C ratings.

What can extinguish Class A fires?

These fuels can be easily extinguished with water, water-based agents such as Class A foam, or dry chemicals.

How to Pump-Type Water Extinguishers operate?

They are 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.

What classes of fires are wheeled dry chemical extinguishers rated for?

They are rated for Class A, B, and C fires based on the dry chemical in the unit.

Do CO2 extinguishers require freeze protection?

They do not require freeze protection

How should dry powder be applied?

Whether a particular dry powder is applied with an extinguisher or with a scoop, it must be applied in sufficient depth to completely cover the burning area in order to create a smothering blanket. The agent should be applied gently to avoid breaking any crust that may form over the burning metal. If the crust is broken, the fire may flare and expose more uninvolved material to combustion. Avoid scattering the burning metal. Additional applications may be necessary to cover any hot spots that develop. If a small amount of burning metal is on a combustible surface, the fire should first be covered with powder. Then, a layer of powder 1 to 2 inches (25 mm to 50 mm) deep should be spread nearby and the burning metal shoveled onto this layer with more powder added as needed. After extinguishment, the material should be left undisturbed until the mass has cooled completely before disposal is attempted.

Why should you never mix dry chemicals?

never mix or contaminate dry chemicals with any other type of agent because they may chemically react and cause a dangerous rise in pressure inside the extinguisher.

What is the primary use for Pump-type water extinguishers?

on ground cover fires although they may also be used for small Class A fires.

What are some disadvantages of dry chemical extinguishers?

the cloud of chemicals may reduce visibility and create respiratory problems just like any other airborne particulate. Some dry chemicals are compatible with foam, but others are not.

What should you consider when selecting a fire extinguisher?

• 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