NEBOSH Certificate in Fire Safety
Element E2: Principles of fire and explosion E2.1 The principles of combustion, fire growth and fire spread Assessment criteria E2.1-E2.3: Describe the principles of combustion in relation to fire safety. The fire triangle
The fire triangle is a simplistic graphic representation for understanding the components necessary for most fires, and whilst the fire triangle model remains valid, in the last few years it has started to be replaced by the Fire Tetrahedron, which provides a more complete model. In addition to the triangle model, the tetrahedron is also described below. The fire triangle illustrates the rule that in order to ignite and burn, a fire requires three elements, heat, fuel, and oxygen. The fire is prevented or extinguished by removing any one of them. Combustion occurs when the three elements are combined in the right mixture.
As part of the fire triangle, fuel is needed for a fire to burn. Until a fire runs out of fuel, it will continue to burn. The fuel can be physically or chemically removed from a fire. An example of physical removal includes removing logs from a campfire using tools such as tongs or a shovel. In the case of a larger fire, such as a wildfire, constructing a fuel break by physically removing or altering vegetation, grass, or shrubs, will ‘remove’ the fuel from the fire. Chemical removal involves interrupting the combustion process by either
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