Fire Chemistry

To exist fire needs three factors: heat, oxygen and fuel. Fire is a chemical reaction accompanied by the creation of heat and light. Combustible substances, when heated to a certain temperature (Ignition Temperature) in normal air (Oxygen) will burn. This burning will create more heat to elevate the temperature, thus causing the fire to gain in intensity and spread.

The three factors are often referred to as the fire triangle. Each of the sides represents one of the factors necessary for combustion to occur. If any one of the factors is removed, the fire will go out.

This is the basis for fire control and extinguishment. Heat can be removed by cooling the burning substance below its ignition temperature. Oxygen can be removed or reduced by excluding the air from the fire surface. Fuel can be removed by stopping the flow of fuel if it was a liquid, or by removing the fuel to a place with no flame.

Portable fire extinguishers extinguish fires by either cooling thereby removing the heat or by smothering thereby excluding the oxygen.