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Fire Extinguishers

When used properly, portable fire extinguishers can help save lives and property. They are also useful in containing small fires until the fire department arrives. Portable home fire extinguishers are not designed to extinguish large or spreading fires. Even against small fires, they are useful only under certain conditions.

When a fire occurs:


  • Notify 911.
  • Sound any alarms.
  • Evacuate immediately.
  • You can try to use a fire extinguisher if you…
  • Know the fire is small and confined.
  • Keep a clear escape route. Don’t let the fire get between you and the exit.
  • Stay low, below the smoke.
  • If you have any doubt, leave the area.
  • Leave if fire grows out of control.
  • Close doors to contain fire.
  • Wait for the fire department’s permission before you re-enter the area.


  • Attempt to extinguish a large or rapidly growing fire.
  • Fight fires without an escape route.
  • Fight fires in a smoke filled room.
  • Fight fires if you are in doubt.
  • Assume the fire is out. Always call the fire department to inspect the area.
  • Ignore any of these steps.

Types of Fires

Not all fires are the same. Different fuels create different fires and require different types of fire extinguishing agents.

Class A fires are fires in ordinary combustibles such as wood, paper, cloth, trash, and plastics.

Class B fires are fires in flammable liquids such as gasoline, petroleum oil and paint. Class B fires also include flammable gases such as propane and butane. Class B fires do not include fires involving cooking oils and grease.

Class C fires are fires involving energized electical equipment such as motors, transformers, and appliances. Remove the power and the Class C fire becomes one of the other classes of fire.

Class D fires are fires in combustible metals such as potassium, sodium, aluminum, and magnesium.

Class K fires are fires in cooking oils and greases such as animals fats and vegetable fats.
Some types of fire extinguishing agents can be used on more than one class of fire. Others have warnings where it would be dangerous for the operator to use a particular fire extinguishing agent.

Types of Fire Extinguishers

Fire Extinguishers also come in different types. Make sure you have the right one for your situation.

Water and Foam fire extinguishers extinguish the fire by taking away the heat element of the fire triangle. Foam agents also separate the oxygen element from the other elements.
Water extinguishers are for Class A fires only – they should not be used on Class B or C fires. The discharge stream could spread the flammable liquid in a Class B fire or could create a shock hazard on a Class C fire.

Carbon Dioxide fire extinguishers extinguish fire by taking away the oxygen element of the fire triangle and also be removing the heat with a very cold discharge.
Carbon dioxide can be used on Class B & C fires. They are usually ineffective on Class A fires.

Dry Chemical fire extinguishers extinguish the fire primarily by interrupting the chemical reaction of the fire triangle.

Today’s most widely used type of fire extinguisher is the multipurpose dry chemical that is effective on Class A, B, and C fires. This agent also works by creating a barrier between the oxygen element and the fuel element on Class A fires.

Ordinary dry chemical is for Class B & C fires only. It is important to use the correct extinguisher for the type of fuel! Using the incorrect agent can allow the fire to re-ignite after apparently being extinguished succesfully.

Wet Chemical is a new agent that extinguishes the fire by removing the heat of the fire triangle and prevents re-ignition by creating a barrier between the oxygen and fuel elements.

Wet chemical of Class K extinguishers were developed for modern, high efficiency deep fat fryers in commercial cooking operations. Some may also be used on Class A fires in commercial kitchens.

Halogenated or Clean Agent extinguishers include the halon agents as well as the newer and less ozone depleting halocarbon agents. They extinguish the fire by interrupting the chemical reaction of the fire triangle. Clean agent extinguishers are primarily for Class B & C fires. Some larger clean agent extinguishers can be used on Class A, B, and C fires.

Dry Powder extinguishers are similar to dry chemical except that they extinguish the fire by separating the fuel from the oxygen element or by removing the heat element of the fire triangle. However, dry powder extinguishers are for Class D or combustible metal fires, only. They are ineffective on all other classes of fires.

Water Mist extinguishers are a recent development that extinguish the fire by taking away the heat element of the fire triangle. They are an alternative to the clean agent extinguishers where contamination is a concern. Water mist extinguishers are primarily for Class A fires, although they are safe for use on Class C fires as well.

WARNING! Using a fire extinguisher on the wrong class of fire can MAKE THE FIRE WORSE!

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