Fire Triangle and Fuel Classifications


The Fire Triangle

Fire Safety, at its most basic, is based upon the principle of keeping fuel sources and ignition sources separate.

Fire TriangleThree things must be present at the same time to produce fire:

1. Enough OXYGEN to sustain combustion
2. Enough HEAT to reach ignition temperature
3. Some FUEL or combustible material

Together, they produce the CHEMICAL REACTION that is fire. Take away any of these things and the fire will be extinguished.


Fuel Classifications

Fires are classified according to the type of fuel that is burning. If you use the wrong type of fire extinguisher on the wrong class of fire, you might make matters worse.

It is very important to understand the four different fire (fuel) classifications:

Class A• Class A: Wood, paper, cloth, trash, plastics — solids that are not metals.

Class B• Class B: Flammable liquids—gasoline, oil, grease, acetone. Includes flammable gases.

Class C• Class C: Electrical—energized electrical equipment. As long as it's "plugged in."

Class D• Class D: Metals—potassium, sodium, aluminum, magnesium.  Requires Metal-X, foam, and other special extinguishing agents.


Most fire extinguishers will have a pictograph label telling you which types of fire the extinguisher is designed to fight.

For example, a simple water extinguisher might have a label like this...

Extinguisher Label...which means it should only be used on Class A fires.