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Principles of Fire

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Fire Triangle

Three components are required for fire to exist.  Heat, Fuel, Oxygen (Air).  These three components of fire create what we call the fire triangle.  If any of these components are removed fire will generally cease to exist.


Examples; a fire source (lighter, match, burning object), chemical heat, sun etc


Examples; wood, gasoline, clothing, combustible metals, plastic etc.

Oxygen (Air):

Examples; generally in fresh air, but can occur from oxidizing reactions (a combustion reaction where oxygen is produced as a byproduct.

Classification of Fire

Class AClass A:   Ordinary Combustibles

Examples;    wood, paper, clothing etc

Class BClass B:   Flammable liquids or gases

Examples;    gasoline, oil, grease etc

Class CClass C:   Energized Electrical Equipment

Examples;    toaster, radio, microwave, television etc 

*If this type of fire is de-energized usually by unplugging it from the source will more than likely fall under a Class A fire.

Class DClass D:   Flammable or Combustible Metals     

Examples;    magnesium, aluminium, sodium etc

class KClass K:   Fires involving vegetable oils, animal oils, or various fats in cooking appliances.  This type of fire deals with commercial cooking operations.

Suppress (Put out)

To suppress a fire, at least one component of the fire triangle must be removed.  An example of removing a component would be to apply water to a Class A fire.  Water applied as an agent on this class of fire will cool the fire thus removing the heat, and may also provide a smothering effect removing the oxygen (air) from reaching the fire. 

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