Principles of Fire

Fire requires 3 elements to exist, known as the fire triangle. If we remove any one of these elements the fire will be extinguished which is exactly what fire extinguishers are designed to do.

Broadly speaking, there are three essentials to every fire. There must be:


a) Fuel, i.e. something to burn;

b) Air, i.e. oxygen to sustain combustion;


c) Heat.

(There are exceptions to this rule, but these are few and highly specialised in character.) The process of combustion can be likened to a triangle whose sides are:

Remove one side of the triangle, and combustion cannot continue. The practice of fire extinguishment is based on this simple principle.

Methods of Extinguishing Fires

The three principle methods of extinguishing fires (i.e. the removal of one side of the "triangle of combustion") are:

a) Starving, i.e. removing the fuel;

b) Smothering, i.e. removing the air (oxygen);

c) Cooling, i.e. removing the heat.

Starving is sometimes preferred, but it is seldom a practicable method. Smothering and Cooling are the methods commonly used.

Multi-Purpose Dry Powder extinguishes Class B and C fires by interruption of the chain reactions of combustion. The glowing carbon residues of Class A fires are extinguished by chemical and physical reactions of the various ingredients of Multra Dry Powder.