All fires are grouped into classes, according to the type of materials that are burning. The classes of fire for the UK and Europe are different to those used in the USA and Australia so remember to always read labels carefully if overseas.

Class A fires are those involving free burning materials, such as paper, wood, fabrics and other textiles, and also plastics

Class B fires involve flammable liquids and solids, such as diesel, petrol, and oils (but not cooking oils), plus solid fuels such as wax

Class C fires involve flammable gases, such as propane, butane and methane

Class D fires involve flammable metals such as sodium, potassium and magnesium

Electrical equipment fires involve electrical equipment such as switchgear or computers. (These are sometimes accidentally referred to as Class E fires, although the category does not officially exist in the UK*)

Class F fires are specific to cooking oils and fats

* 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.

Fire Extinguishers: Colours, Letters, Numbers and Pictures

In order to standardise markings on fire extinguishers across Europe, information is presented in several ways on a fire extinguisher.

1. Every fire extinguisher is colour-coded for easy reference
2. The extinguisher’s fire rating is shown both as a letter (such as A or B) and also as a pictogram. In addition, the fire extinguisher will also bear a pictogram if it is suitable for use on electrical equipment fires
3. The precise fire rating for Class A and B fires is expressed as a number and letter combination, such as 34B
4. There are clear operating instructions on how to use each types of extinguisher. To see what each fire extinguisher looks like, see our guide to types of fire extinguisher

In addition, a quality UK fire extinguisher should be clearly marked with:

• The fire rating
• a BS (BSI) Kitemark, indicating BAFE (British Approval for Fire Equipment) approval
• a CE mark

These marks confirm that your fire extinguishers comply with the Pressure Equipment Directive (PED) and are BAFE (British Approval for Fire Equipment) approved.

Choosing the Right Fire Extinguisher for Your Fire Risk
As you might expect, the letter coding or rating on a fire extinguisher label corresponds to the fire class(es) it can be used on. The numbers before the rating, e.g. 13A, indicate the size of fire that can be extinguished under test conditions.

Generally, the larger this number, the larger the fire that the extinguisher can extinguish. However, never underestimate the size of any fire you may try and deal with. If in any doubt, get out, stay out, and call your local Fire Brigade immediately.

Class A

Class A rating fire extinguishers are often water-based, and are highly effective in extinguishing burning materials found or stored in an office or warehouse, for example. Water-based Class A extinguishers may also have additives to make them more effective.

The number before the letter A such as 13A indicates the length of a wooden crib test fire (1.3 metres in this case) successfully extinguished under rigorous test conditions. If you need a 13A rating, anything higher such as 21A will even better.

Class B

Class B rating fire extinguishers are usually foam (AFFF) fire extinguishers or powder. These extinguishers work by not only extinguishing flames but also sealing in any potentially dangerous vapours.

The number before the letter B such as 144B indicates the size of the flammable liquid test fire that can be extinguished under test conditions. The higher the number, the bigger the fire.

Class C

Class C rating fire extinguishers will be dry powder fire extinguishers but flammable gas is a strange one in that, if out out without the gas supply being turned off, the escaping gas is much more dangerous.

Class D

Class D rating fire extinguishers are highly specialised extinguishers, designed to be used on specific metal fires with such exotic names as M28, L2 and Purple-K. They will have a long lance with a low velocity applicator on the end.

Fires Involving Electrics

Electrical equipment fire extinguishers are specially designed for use on live electrical equipment without harming the fire extinguisher user. While a powder fire extinguisher is non-conductive and safe to use, the most popular fire extinguisher for use on electrical equipment fires is carbon dioxide, which extinguishes flames without causing further damage.

Class F

Class F rating fire extinguishers, known as wet chemical fire extinguishers, are specifically for fires involving cooking oils and fats.

Multi-Rating Fire Extinguishers

Many fire extinguishers you see in public areas and offices can be used on two or more classes of fires. For more details, see our guide to multi-rating fire extinguishers.