Office of Environmental Health and Safety

Student in Lab

Explosion and Fire Emergencies

Oxygen, heat and fuel are necessary for the chemical reaction that produces a fire. These three things form what is called the fire triangle. Take one of these three things away and the fire can be extinguished. Explosions are followed by a fire. Use fire emergency procedures in the event of a fire.


Fuels are classified into the following four categories:

  • Class A
    Solid combustible materials that are not metals: Wood, paper, cloth, trash, plastics.
  • 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.
  • Class D
    Metals: potassium, sodium, aluminum, magnesium. It takes special extinguishing agents (Metal-X, foam) to fight such a fire.

How to Use a Fire Extinguisher

To use a fire extinguisher remember the acronym PASS, which stands for Pull, Aim, Squeeze, and Sweep. Always use an extinguisher that is appropriate for the fuel type.

Here is an excellent resource for understanding the proper technique. And a good video is embedded below.