These are the cheapest of the portable fire extinguishers and are for use on Class A, solids such as wood, paper, leaves, sugar, straw, plastic, etc. Also available are the water spray and water with additive extinguishers, these both have the advantage of being smaller and electrically non-conductive over the standard 9Ltr water jet extinguisher.
Fire extinguishers within commercial buildings, churches, stadiums, etc are required by law and in most circumstances, your insurance will stipulate that they are both installed and maintain within your building. Further to this, they are installed to give the occupier a chance to extinguish or control small fires, remember most fires start small and can be extinguished with a portable fire extinguisher.
Fire extinguishers come in various types, sizes, and versions, it is important that the correct extinguisher are installed to cover the risks present. The extinguisher types are
Foam extinguishers are for use on the same Class A solids as water extinguishers, but can also be used on Class B flammable liquids such as petrol, diesel, paraffin, white spirit, paint and includes liquefiable solids such as wax, grease, margarine, and shoe polish. Also available are the foam spray extinguishers, these both have the advantages of being smaller, lighter and electrically non-conductive over the standard 9Ltr branch pipe type extinguisher. Foam is not recommended for cooking fat/oil fires.
ABC Dry Powder extinguishers are for use on the same Class A, Class B fires as defines above but can also be used on gas fires such as propane, butane, acetylene, hydrogen, ammonia, methane, and ethylene. It is a versatile extinguisher but is not ideal in confined spaces or in buildings as it reduces visibility and can cause damage from its messy extinguishing agent. There are special powder extinguishers on the market to cover class D, metal fires. These include magnesium, aluminium, titanium, sodium, lithium, caesium, manganese, cobalt, cadmium and potassium.
The Wet Chemical or Class F fire extinguisher is the only extinguishers designed for fires involving cooking fats and oils. The extinguisher has a low velocity applicator come lance, this means the operator is kept away from the fire and the risk of splashing the oil about when applying the foam solution is reduced. These extinguishers are electrically non-conductive and have been designed with chip shops, restaurants, and fast-food outlets in mind.
Co2 extinguisher provides suburb fire fighting properties when dealing with fires involving electricity. As the extinguishing agent is a gas it can cases and cabinets containing electrical items very quickly and easily. Ideal for fires within photocopiers, computers, electrical switchgear, and computer screens. It is a very clean extinguishing agent. Co2 can be used on flammable liquid, Class B fires. Extreme caution must be taken not to put the discharge horn too close to the burning liquid, they also have no post fire security and the liquid could burst back into flames.
Starving is not always practice but can be the preferred method.
Cooling and smothering are methods that are most widely used.
Some fire extinguishers such as Dry Powder interrupt the chain reactions of combustion of Class B and C Fires and extinguish Class A fires by chemical and physical reactions of the various ingredients of the Dry Powder extinguishing media.