Page 346 - IGC BOOK

10.1 Principles of Fire

Fire

Fire is a chemical reaction. It occurs when fuel, oxygen and an ignition source are brought together.
These three elements are referred to as the ‘fire triangle’

The Causes of Fire

For a fire to initiate all the three elements must be present in equal proportion for a fire to sustain,
removal of any of these elements will extinguish the fire.

Starving Cooling
(Reducing the fuel) (Reducing the heat)

Smothering
(Reducing the oxygen)

Fuel - a combustible material or substance that is consumed during the combustion process.
In a typical workplace, fuels can include paper and cardboard; wood and soft furnishings;
structural materials; petrol and diesel fuels, butane, acetylene and other gases, solvents and
other chemicals.

Oxygen - consumed during combustion when it is chemically combined with the fuel. Oxygen
is present in air at a concentration of 21%. During a fire oxygen can also come from other
sources, including certain oxygen-rich chemicals (usually called oxidising agents), such as
ammonium nitrate.

Sources of ignition (heat) - a heat or ignition source is essential to start the combustion
process. Once combustion has started it generates its own heat which is usually sufficient to
keep the fire burning (in other words once the fire starts the heat source can be removed and
the fire stays alight). Some examples will be described later.

ENSIGN | Unit IG2 – Element 10 –Fire 1