NEBOSH Certificate in Fire Safety and Risk Management - FC1 E2
Element 2: Principles of fire and explosion
Element Overview
There are 5 learning outcomes in this unit:
2.1 Explain the principles of the combustion process in relation to fire safety
2.2 Explain the principles and conditions for the ignition of solids, liquids and gases
2.3 Identify the classification of fires
2.4 Describe the principles of fire growth and fire spread
2.5 Outline the principles of explosion and explosive combustion.
2.1 Explain the principles of the combustion process in relation to fire safety
The fire triangle concept
Fires need three things to start.
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Air/Oxygen
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Fuel
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Heat
They are represented in a triangle called the fire triangle. To start a fire you need to have all three present. If there's just air and fuel or air and heat, a fire cannot start. To extinguish a fire one of these three elements needs to be removed.
The Fire Triangle
Heat
Oxygen
Fuel
Heat
Heat acts as a source of ignition. Which means anything that produces heat and comes in to contact with a combustible material can potentially start a fire.
Fuel
Most materials are combustible under the correct conditions or when exposed to enough heat. All materials have a temperature at which they will burn, some higher than others. Fuels can be broken into solids, liquids and gasses.
Oxygen
Oxygen is essential for the combustion process. The air around us is enough to support the combustion process. Once the surrounding oxygen depletes the fire will cease.
Fire Extinguishers
Fire extinguishers work by preventing the fire from getting heat or fuel or oxygen/air. If you take any one of these elements away you stop the fire from starting or growing.
Example:
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Water filled extinguishers lower the temperature until the fire goes out.
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Foam extinguishers stop the oxygen getting to the flames.
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The fire blanket does the same when thrown over a blazing chip pan.
