A long time ago, the fire protection industry recognized the need to classify extinguishers according to the many kinds of burning materials encountered in a fire. For example, Class A, water-type fire extinguishers cannot be used on the electrical fires because the extinguisher operator could be seriously injured by the conduction of electricity by the stream of water from their extinguisher. Instead, a Class C fire extinguisher will work best. Another example, a raging fire in a manufacturing plant with flammable metals, such as magnesium, should be fought with a Class D fire extinguisher (see chart below).
- Class A: Fires that involve wood, cloth, rubber, paper, and some types of plastics.
- Class B: Fires that involve gasoline, oil, paint, natural and propane gases, and flammable liquids, gases, and greases.
- Class C: Fires that involve all the materials found in Class A and B fires, but with the introduction of an electrical appliances, wiring, or other electrically energized objects in the vicinity of the fire.
- Class D: Fires that involve combustible metals, such as sodium, magnesium, and potassium.
The following video tutorial by OSHA, added to this article on 6/24/15, offers helpful information on how to use a fire extinguisher. Especially important is the portion of this video that deals with when to use and not to use certain types of fire extinguishers.
Besides knowing what type of fire you're likely to encounter, it's also important to know what kind of extinguishing agent your fire extinguisher should have in it. This is because certain extinguishments will work only on certain kinds of fires. Others can actually aggravate the situation, causing an even more critical situation. (read more).