Types of Fire Extinguishers, Their Parts and When to Use Them

In an emergency, a fire extinguisher can save lives. Knowing how to use this simple yet effective fire prevention tool is important for the protection of yourself and others. In addition, it's critical to know the difference between various types of fire extinguishers, since each kind is effective for different sorts of fires.

Red fire extinguisher tank on orange wall
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Types of Fire Extinguishers, Their Parts, and When to Use Them

Fire and Fire Extinguisher Basics

Fire extinguishers work by removing one or more of the parts of what's known as the fire triangle. These parts are heat, oxygen and the chemical reaction that causes a fire. Which type of extinguisher you need depends on what caused the fire.

Fires can be classified into a variety of categories depending on their cause and their fuel. Class A fires are caused by ordinary combustibles like paper, cloth, wood, rubber or some plastics. Class B fires occur in flammable liquids or gases, such as gasoline, petroleum grease, oil, tar, paints, solvents, alcohols, propane or butane. Class C fires involve live electricity and are commonly caused by malfunctions with computers, transformers, servers, motors or appliances. Class D fires are caused by combustible metals like magnesium, titanium or sodium. Finally, Class K fires are caused by cooking oils or greases. Fire extinguishers are usually rated to combat certain types of fires.

Fire extinguishers are comprised of a metal or other sturdy canister in which the extinguishing agent is held, a nozzle and/or a tube, a lever and a pin. To use an extinguisher, pull the pin that's located at the top of the nozzle. This will enable the lever to move or be squeezed. Then, aim the nozzle or tube at the blaze you need to fight and squeeze the lever to release the extinguishing agent. Follow the manufacturer's specifications as regards the proper distance from which to engage the extinguisher. Sweep the nozzle or tube back and forth across the fire until you have put it out.

In any emergency involving a fire, you should contact your local fire department immediately, even if you plan to use an extinguisher. In the event that you're unable to put the fire out yourself, help will already be on its way.

Types of Fire Extinguishers

Fire extinguishers should always be labeled with the class of fire they prevent. Before attempting to use one, check this label for direction.

Water and foam fire extinguishers work by removing the heat portion of the fire triangle. The foam also helps to keep oxygen away from other chemical elements, preventing further burning. This type of extinguisher should only be used for Class A fires. They could pose a risk of combustion or electric shock if used on B or C fires.

Carbon dioxide extinguishers use CO2 and cold temperatures to eliminate the oxygen that a fire needs to survive. Typically, these won't work on Class A fires. They're best for B and C fires.

Dry chemical extinguishers work on multiple fire types and use a chemical reaction to interrupt the fire's combustion. Many fire extinguishers today use a multipurpose dry chemical rated for A, B and C fires. However, other extinguishers of this type are only effective on B and C fires.

Wet chemical extinguishers create a barrier between the chemicals involved in a fire's reaction and are most effective for Class K burns. In some instances, they may be rated for Class A commercial kitchen fires.

Clean agent extinguishers use environmentally friendly chemicals and are effective on Class A, B and C fires. If your clean agent extinguisher is handheld, it may only be rated for B and C fires.

Dry powder fire extinguishers are only effective on Class D fires involving metals. Don't attempt to use them for other sorts of fires.

Water mist extinguishers are best for fighting Class A fires where contamination is a concern since no harmful chemicals are used. They may be rated to treat C fires, as well.

Finally, cartridge-operated dry chemical extinguishers work much the same way as do ordinary dry chemical extinguishers. However, these models are effective on A, B and C fires, whereas the latter is occasionally only effective for B and C blazes.

Regardless of which type of fire extinguisher you have, it should be kept only until its expiration date and inspected as marked. Learn how to use yours so you're prepared in the event of an emergency.