Fire is a chemical reaction involving rapid oxidation (burning) of fuel. The following three elements must be present at the same time in order for a fire to start:
FUEL – Any combustible material (flammable gases, liquids, solids). Most solids and liquids must vaporize before they will burn.
OXYGEN – Sufficient oxygen (present in the air, oxidising substances) must be present in the atmosphere surrounding the fuel for fire to burn.
HEAT – Sufficient heat energy (hot surfaces, electrical equipment, smoking, naked lights) must be applied to raise the fuel to its ignition temperature.
The combination of these three elements is frequently referred to as the ‘fire triangle’. The removal of any one of these elements will result in the fire being extinguishers or no fire at all. Fire extinguishers will extinguish a fire by removing one or more elements of the fire triangle.