Classification of Fuels

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 A - Wood, paper, cloth, trash, plastics Solid combustible materials that are not metals.
	Class B - Flammable liquids: gasoline, oil, grease, acetone Any non-metal in a liquid state, on fire.
	Class C - Electrical: energized electrical equipment As long as it's "plugged in," it would be considered a class C fire.
D	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.

Next, we'll look at the different types of fire extinguishers and the class of fire each is designed to extinguish.