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Fire Tetrahedron

Last updated: September 26, 2018

What Does Fire Tetrahedron Mean?

The fire tetrahedron is a geometric representation of the four properties that must be necessary for a fire to occur within a given situation. These properties include fuel, heat, an oxidizing agent (usually oxygen found in ambient air), and an uninhibited chemical reaction.

The purpose of the fire tetrahedron is to provide a simple explanation of how fire works and thus make clear how to extinguish a given type of fire in an emergency. If any element of the fire tetrahedron is suppressed or removed, the fire itself will be extinguished.

Safeopedia Explains Fire Tetrahedron

The fire tetrahedron is an update of the fire triangle, which referred solely to fuel, heat, and an oxidizing agent. The chemical reaction was added for the purpose of communicating the fact that a fire must produce a continuous exothermic (heat-generating) chemical reaction in order to ignite more fuel and sustain itself.

The four elements of the fire tetrahedron are the four constituent elements necessary to make a fire, with each element relying on the presence of the other three elements to work. Fuel refers to any element that can undergo combustion. Heat is necessary to cause the fuel to release the vapors that will be ignited. An oxidizing agent, usually the oxygen found in air, is the component that the fuel vapor reacts with in order to combust. Finally, the exothermic chemical reaction caused by the combustion creates more heat, which releases more fuel vapor, which then combusts through a reaction with the oxidizer, thus perpetuating the fire.

Methods of preventing or extinguishing a fire can be attached to each individual aspect of the fire tetrahedron. For instance, the risk of a workplace fire can be reduced through proper storage of fuel, and a natural gas fire would be extinguished by turning off the supply of gas to an area. The use of water to cool down a fire is one of the most commonly known methods of extinguishing a fire, although some substances may produce fires that are hot enough that they cannot be adequately cooled down by water alone. Oxidizing agents can be removed by smothering a fire with dirt or a fire blanket, or by replacing or reducing the concentration of oxygen in the atmosphere by introducing another non-combustible gas into the environment.

In workplaces with sensitive electrical equipment, fires may need to be extinguished in a manner that cannot damage the equipment. In this instance, a halon-gas extinguishing system may be used to disrupt the chemical reaction necessary to sustain the fire.


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