How To Use a Fire Extinguisher
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, plasticsSolid combustible materials that are not metals.
Class B - Flammable liquids: gasoline, oil, grease, acetoneAny non-metal in a liquid state, on fire.
Class C - Electrical: energized electrical equipmentAs long as it's "plugged in," it would be considered a class C fire.
Class D - Metals: potassium, sodium, aluminum, magnesiumUnless 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.
