Britain has a series of standards that act as legal requirements for the design, production, labelling and maintenance of fire extinguishers. These changed in 1997 to meet European-wide standards, making it easier for manufacturers in one country to produce extinguishers they could legally sell in another country. The main difference this made in Britain was the way that colours indicate the material used in the extinguisher.
Fire extinguishers sold up until 1997 were required to meet British Standard (BS) 005423. Since 1997, they must meet BS 7863. The only significant change between 05423 and 7863 was the colouring scheme. For administrative purposes, extinguishers sold since 1997 also come under BS EN3, which formally brings the British standard in line with European standards.
Until 1997, British extinguishers generally followed a colour code to identify their contents. Red extinguishers contained water, cream extinguishers contained foam, blue extinguishers contained powder, black extinguishers contained carbon dioxide and green extinguishers contained halon. In 1997, this was replaced by the requirement of BS EN3 that all extinguishers should be red. BS 7863 allows British fire extinguishers to have up to 10 per cent of the surface colour coded in line with the pre-1997 colours.
British Standard 5306-3 covers maintenance of fire extinguishers. It requires weekly checks to see if the extinguisher has been operated or if it has suffered visible damage that could make it unsafe. It also requires a basic annual service and an extended service every five years.
British Standards divide fires into five categories, and extinguisher labelling must state which they are suitable for. Category A is for freely burning materials such as paper or wood; B is for flammable liquids other than cooking oil; C is for flammable gasses; D is for flammable metals and F is for cooking oil and fats. Electrical fires are not classed, as they can be safely extinguished by any extinguisher, although the electricity supply must be isolated when using a water extinguisher.
Extinguishers carry a fire rating that corresponds to the size of fire they have extinguished in testing. The higher the rating, the larger the size of fire the extinguisher can handle. The maximum rating per class of fire varies: class A goes up to 55, while class B goes up to 233. Extinguishers display the rating alongside the class of fire they are designed for; for example "13A" or "55B."