Fires
1. Classification of Fires and Methods of Extinction
Fires are classified into five classes according to the type of fuel involved:
Class A:
Caused by solid fuels that leave ashes and embers on burning, such as wood, paper, straw, natural fibres, etc. The most appropriate method for extinguishing these fires is by cooling.
Class B:
Caused by liquid fuels or fuels that distil liquid as a result of heat, such as tar, gasoline, oils, grease, solvents, etc. The most appropriate method for extinguishing these fires is by suffocating or inhibiting the chain reaction.
Class C:
Caused by gaseous fuels, such as acetylene, butane, propane, methane, etc. The most appropriate method for extinguishing these fires is to eliminate the exit of the gas, closing valves, although they may also be extinguished by suffocating or inhibiting the chain reaction.
Class D:
Also known as “special fires”, these are caused by certain chemical products or by combustible metals, such as sodium, potassium, pulverised aluminium, titanium, zirconium, lithium, etc. Each product has a suitable system of extinction.
Class E:
Also known as “electrical fires”, these are caused in electrical equipment or installations or any fire that is produced in the presence of electrical voltage above 25 V. The supply of electricity must be cut off and the fires are to be extinguished by suffocation using non-conducting extinguishing agents.
