Before you can understand how a fire is extinguished, you need to first understand the theory of Fire
4 Elements must be present for a fire to occur fire-tetrahedron
- Fuel
- Heat
- Oxygen
- Chemical reaction
A fire is extinguished by removing one or more of these 4 elements from the combustion process
Extinguishing the fire:
Since 4 elements must be present for the combustion process to occur, a fire can be extinguished by removing one or more of these 4 elements
In practical firefighting terms this translates as starvation, cooling, smothering and interference
- Starvation – is the process of depriving the fire of fuel ie. Combustible materials
- Cooling – is the process of depriving the fire of heat eg. By applying a substance such as water that will absorb heat from the fire and thereby reduce the fires temperature below the critical level needed to sustain the fire
- Smothering – is the process of depriving the fire of the oxygen needed to sustain the combustion process
- Interference – is the process of applying extinguishing agents to the fire that inhibit the chemical chain reaction at the molecular level
There are many different types of extinguishers, all of which are very specific to fighting certain classes of fire. More information on classes of extinguishers can be found here.
Classes of Fire:
| Class A | Carbonaceous | Wood, Paper, Cloth, Rubber & Plastics |
| Class B | Liquid Fires | Petrol, Kero, Oil, Tar, Paint & Wax |
| Class C | Gaseous Fires | LPG, Propane & Butane |
| Class D | Metal Fires | Aluminium, Magnesium & Sodium |
| Class E | Involving Electrical Equipment | Kettles, Irons, Toasters, Electric Blankets, TV’s & Appliances |
| Class F | Fat Fires | Cooking oils & Fats |