The Fire Triangle: Understanding Fire Suppression

The fire triangle—heat, fuel, and oxygen—is the simplest model for understanding what fires need to burn and how to extinguish them. Every fire suppression technique targets one or more sides of this triangle.

Cooling removes heat energy from the fire. Water is the most common cooling agent. As water converts to steam at 212 degrees Fahrenheit, it absorbs enormous amounts of heat, dramatically reducing the temperature of the fire environment below the ignition threshold.

Smothering removes oxygen. Covering a small fire with a fire blanket, lid, or non-flammable material cuts off the oxygen supply. Dry chemical fire extinguishers displace oxygen as well as interrupting the chemical reaction of combustion.

Removing fuel eliminates the energy source. In large wildfires, this means creating firebreaks—strips of cleared vegetation that starve the fire of fresh fuel. In controlled burns, fuel removal is achieved by setting small, deliberate fires ahead of the main fire's path.