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Extinguish a fire

A fire is extinguished by destroying the fire tetrahedron in the following ways:

Cooling (removal of heat)

Where the temperature of the material is reduced to below ignition point. An example is the use of a fire hose directly onto the fire. This is a direct attack on the heat side of the fire tetrahedron. When properly applied, it absorbs the heat from the fuel, and absorbs much of the radiation. When attacking the fire with a hose line, water in the proper form is directed onto the main body of the fire 
to achieve the quickest heat reduction. Water spray can be a highly efficient extinguishing agent, and for complete extinguishment the water must be applied to the base of the fire. Uf04

Starving (removal of fuel)

Where the burning items are physically removed from the immediate area. Here it might be a burning curtain thrown over the side, or in the case of liquid or gaseous fuel, the supply valve is shut off. This is a direct attack on the fuel side of the fire tetrahedron

Smothering (remove/reduce oxygen)

Where the oxygen is reduced or replaced by another gas. This method is difficult in an open area where the gaseous smothering agents such as carbon dioxide would be blown away. A simple example of smothering is the covering of a burning garbage bin with a tight cover; the fire consumes the oxygen and is extinguished. This is an attack on the edge of the fire tetrahedron where the fuel and oxygen sides meet.

Breaking the chain reaction

A fire can be extinguished very rapidly if the chain reaction sequence is broken. The extinguishing agents commonly used to attack the chain reaction are dry chemicals, dry powders and halons/BCF (the latter are being phased out on environmental grounds). These agents directly attack the molecular structure of compounds formed during the chain reaction sequence.




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