Matching Classes of Fire with the proper type of Extinguisher

• Some extinguishers are suitable for one class of fire only;
• Others can fight two or even three classes of fire;
• NO single fire extinguisher is capable of fighting all 4 classes of fire.

To understand which type of fire extinguisher is needed with each particular fire, you must first understand the extinguishing agents used by each class of extinguisher.

Agents by Class of Fire Extinguisher

Class A 

• Water;
• Chemical Foam;
• Dry Chemical.

Dry Chemical, Carbon Dioxide (CO2) and Halon can be used on Class A fires, but may not be effective on their own.

They may need to be supplemented with water.

“Class A” extinguishers containing water must NEVER be used with on fires which are burning;
– Oils
– Grease
– Tar
– Gasoline
– Paints
– Live Electrical Equipment

Class B

• Carbon Dioxide (CO2);
• Halon²;
• Dry Chemical;
• Aqueous Film Forming Foam (AFFF)

Extinguishers containing Aqueous Film Forming Foam must NEVER be used on Electrical Shock hazard fires (Class C) or on Class D fires.

AFFF extinguishers are heavy & are subject to freezing if not kept in a continuously heated area.

Class C

• Carbon Dioxide (CO2)
• Halon²
• Dry chemical

Extinguishers using one or more of the above listed ingredients (including AFFF) on most flammable materials, smother the fire by separating the oxygen from the fuel and stopping the chemical reaction.

Class D

• Dry Powder (For specific combustible metal)

Certain combustible metals burn at much higher temperatures and give off sufficient oxygen to support combustion.
They may REACT VIOLENTLY with water or other chemicals.

“Dry Powder” MUST NOT be confused with “Dry Chemical”
– Dry Chemical agents may cause an explosive reaction with combustible metals.