the solution used in wet chemical extinguishers is alkaline, which means it can cause corrosion of some metals. Extinguishers in commercial or public buildings should be visually inspected monthly for damage or pressure loss and should be serviced in line with the manufacturer’s instructions or to BS 5306-3. Water, foam and powder extinguishers have to be discharged and refilled every five years. CO2 extinguishers must be refurbished after ten years. One exception, however, are the kitemarked P50 servicing-free extinguishers which only need refurbishment after ten years and do not require maintenance within the ten years (other than the monthly visual inspection and a recorded yearly visual inspection by the owners). carbon dioxide is a non-conductor, so can be used on live electrical equipment (so is often suitable for server rooms).

Combustible cooking fires require a special wet chemical extinguishing agent. Oil residues and grease are commonplace in catering and commercial kitchens and have the ability to reach extremely high temperatures and can re-ignite easily. When choosing the right fire extinguisher, it is important to know that no single type of fire extinguisher can be used on all types of fires. Your fire risk assessment should identify which types of fires are most likely to occur in your building/premises, making this a good place to start. In the guidance documents provided for fire safety legislation (England and Wales/Scotland/Northern Ireland) the recommendation is that part of an employers’ measures for protecting their staff and others from fire is to install independently tested and certificated fire extinguishers. Fires involving combustible metals such as, lithium, magnesium, aluminium, sodium, potassium, and their various alloys, class ‘D’ fire extinguishers are used. BS5306-8 (Clause 7.1) states that for fires involving electrical equipment there is no recognized classification for this additional type of fire. Electricity in itself does not burn but can cause fires in class A, B, C, D and F materials.water is an electrical conductor, making the extinguisher unsuitable if the class of fire has an electrical supply, or for use near live electrical equipment. Foam extinguishers work similarly to water extinguishers by having a cooling effect on the fuel. The foaming agent works by creating a barrier between the flame and the fuel. Other extinguishers will be predominantly signal red with a label, band or circle covering at least 5% of the surface area of the extinguisher in a second colour indicating the contents of the extinguisher. produces a foam that acts initially as a blanket, covering the surface area and smoothering the fire. Electrical fires are not given their own full class, as they can fall into any of the classifications. After all it is not the electricity burning but surrounding material that has been set alight by the electric current.

Both the Home Office and the Fire & Rescue Services recommend extinguishers approved to the European Standard BS EN3 and compliant with BS 5306-10 (formerly BS 7863) colour coding code of practice. There is no single fire extinguisher which works on all classes of fire. What are the different classes of fire?

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The number of fire extinguishers you will need depends on the size of your premises and whether you operate in a low or high risk business. A risk assessment should be carried out to determine the exact number you should install. All extinguishers capable of extinguishing class F fires have a rating based on 4 benchmark tests using 5, 15, 25 and 75 litres of sunflower oil. The oil is heated to auto-ignition and allowed to pre-burn for 2 minutes. The fire is then extinguished and no re-ignition shall occur within 10 minutes of extinguishing the fire. Fires have different classifications as different extinguishing medium (water, carbon dioxide etc) react differently to types of fire and only the appropriate extinguisher should be used to attempt to extinguish a fire. The testing and maintenance of fire extinguishers is essential and required by law to ensure they work if and when they’re ever needed. Following these activities the extinguisher must be labelled appropriately to confirm their fitness for purpose.