Classification of Fuels
Fire Triangle
[Fire Triangle]
How To
[How to]

Not all fuels are the same, and if you use the wrong type of fire extinguisher on the wrong type of fuel, you can, in fact, make matters worse. It is therefore very important to understand the four different classifications of fuel.

Class AClass A - Wood, paper, cloth, trash, plastics
Solid combustible materials that are not metals.

Class BClass B - Flammable liquids: gasoline, oil, grease, acetone
Any non-metal in a liquid state, on fire.

Class CClass C - Electrical: energized electrical equipment
As long as it's "plugged in," it would be considered a class C fire.

Class D - Metals: potassium, sodium, aluminum, magnesium Unless you work in a laboratory or in an industry that uses these materials, it is unlikely you'll have to deal with a Class D fire. It takes special extinguishing agents (Metal-X, foam) to fight such a fire.

Most fire extinguishers will have a pictograph label telling you which fuels the extinguisher is designed to fight. For example, a simple water extinguisher might have a label like the one below, indicating that it should only be used on Class A fuels.

Class D