Fire extinguishers are active fire protection devices used to extinguish or control small fires, often in emergency situations. It is not intended for use on an out-of-control fire, such as one which has reached the ceiling, endangers the user (i.e., no escape route, smoke, explosion hazard, etc.), or otherwise requires the expertise of a fire department. Typically, a fire extinguisher consists of a hand-held cylindrical pressure vessel containing an agent which can be discharged to extinguish a fire.
Fire extinguishers are divided into handheld and cart-mounted, also called wheeled extinguishers. Handheld extinguishers are easily portable by hand. Cart-mounted units are most commonly found at construction sites, airport runways, heliports, as well as docks and marinas.
The UK recognizes five fire classes:
Class A fires involve organic solids such as paper and wood.
Class B fires involve flammable or combustible liquids, including petrol, grease, and oil.
Class C fires involve flammable gases.
Class D fires involve combustible metals.
Class F fires involve cooking fat and oil.
In the UK the use of Halon gas is now prohibited except under certain situations.
EN3 does not recognise a separate electrical class. A powder or CO2 extinguisher will bear an electrical pictogram as standard signifying that it can be used on live electrical fires (given the symbol E in the table). If a water-based extinguisher has passed the 35 kV test it will also bear the same electrical pictogram – however, any water-based extinguisher is only recommended for inadvertent use on electrical fires.