Fire Extinguisher Types
There are a number of different extinguishing agents on the market, developed and designed to extinguish different types of fire. Fires are classified according to the combustible material involved.
Classes of Fire:-
Class A - Fires involving solid materials, usually of an organic nature in which combustion normally takes place with the formation of glowing embers.
Class B - Fires involving liquids or liquefiable solids.
Class C - Fires involving gases.
Class D - Fires involving metals.
Class F - Fires involving fats and cooking oils
Note: Unlike other continents, the European EN3 rating system does not recognise a Class E fire classification, as electrical equipment is often the cause of a fire, rather than a fire type. So, modern fire extinguishers specify whether they should be used on electrical equipment, rather than bearing a Class E rating.
Good for tackling fires involving burning paper, wood and soft furnishings, as the water soaks into the materials (Class A fires). This type of extinguisher does not leave a residue but does have a comparatively low rating. Due to this factor water extinguishers are large and heavier to overcome their lacking in fir fighting power. It is important to remember that water is an electrolyte and conducts electricity. Care must therefore be taken with regards to accidental use on mains power.
Note. Certain manufacturers produce water extinguishers that have an element of protection against electrocution (e.g. water with additives, water spray) but in most cases they designed for inadvertent contact with electrical equipment and we would not advise these as an alternative to an electrical type extinguisher (e.g. CO2 and powder). Please refer to extinguisher manufacturers specifications.
Foam (AFFF) Extinguishers
The AFFF fire extinguisher (pronounced A triple F) is suitable for use on class A and B fires. This means that in addition to being able to tackle combustible organic materials such as paper, card, wood and textiles, it is also able to tackle fires involving flammable liquids such as petrol or oils. They are therefore quite a flexible extinguisher and can be used in any situation where you would normally use a water extinguisher, so are good for general all round use.
Note. Most AFFF extinguishers are fitted with an atomising nozzle which gives the user some protection against electric shock from inadvertent contact with electrical equipment. This is usually ONLY for accidental contact with electrical equipment and therefore we would not recommend this type of extinguisher as an alternative to an electrical type of extinguisher (e.g. CO2 or powder). Please refer to extinguisher manufacturers specifications.
Carbon Dioxide (CO2) Extinguishers
Containing only pressurised CO2 gas and leaving no residue. This type of extinguisher is suitable for use on fires involving burning liquids (Class B fires), but is also an excellent solution for quenching fires involving computer equipment and other electrical appliances, as it does not cause damage to the electrical items and does not cause the system to short circuit. It is important to remember that when using CO2 extinguishers there is a possibility that once the gas has floated away the fire may reignite if the source of the fire is not removed (e.g. switching off the power supply).
Not. Be aware that CO2 extinguishers that are not fitted with double-lined swivel horns may cause your fingers to freeze to the horn during the deployment of the CO2 gas.
Powder (ABC) Extinguishers
(ABC) Powder fire extinguishers are fairly versatile and suitable for use against class A, B and C types of fire and additionally, they do not conduct electricity (i.e. can be used on wood, paper, textiles, liquid, gaseous and electrical type fires.
Although a very powerful and versatile extinguisher it’s very important to be aware of the negatives when discharging a powder extinguisher, some of which are; dense powder in the atmosphere can dramatically reduce visibility and cause breathing difficulties, powder can be very invasive and destructive to sensitive I.T. equipment, very messy which can lead to a lengthy and costly clean up. Bearing these factors in mind, we urge careful consideration on whether there is a better alternative to powder and if not where best to install this extinguisher.
Wet Chemical Extinguishers
Suitable for use with fires involving burning oil and deep fat fryers (Class F fires). These extinguishers come with a special application lance which lays a cooling layer of foam on top of the burning oil.
The chemical spray released by the extinguisher works by starting a chemical reaction that combines the discharge with the cooking fat or oil to form a cake of soap like emulsion which cools the fire. These extinguishers are probably the type best suited to fires in the kitchen and are essential for restaurants. They’re usually also suitable for fighting fires involving wood, paper and textiles (please refer to manufactures specifications) although not suited for use on flammable liquids, gases and metals.
Special Powder Extinguishers
These specialist powder extinguishers are designed to tackle fires involving combustible metals (class D fires) such as lithium, magnesium, sodium or aluminium when in the form of swarf or powder.