A fire extinguisher is an active fire protection device used to extinguish or control small fires, often in emergency situations. A fire extinguisher is described by its contents:

See, Hazard- Fire and thermal radiation

At present these use:

Extinguishers conforming to British Standard BS EN3 range from approximately 2kg to 20kg, the latter being considered the maximum a person can satisfactorily carry and use effectively.

Before selecting a fire extinguisher as an appropriate media:

• If using a self-aspirating foam extinguisher on a contained fire, direct the foam against a vertical surface such as a wall or side of the container if possible
• On a running fuel fire, ensure that the foam from a foam extinguisher falls gently onto the surface to build up the blanket and, if possible, make a break between the already burning liquid and that not yet ignited
• When using a powder extinguisher, be aware that although most powders are of minimal toxicity, some can be dangerous if inhaled for some time. If discharging a powder extinguisher in a confined space, personnel should ensure adequate ventilation is present when conditions permit or use respiratory protection equipment (RPE)
• Be aware that while powder extinguishers can suppress a fire, they do not normally form an inert atmosphere and will rapidly settle out once application stops. Firefighters must always be aware of re-ignition, especially on class B fires, and be ready to begin powder application again or use another suitable medium
• Realise that a powder extinguisher is not good at penetrating hidden spaces and may cause damage to delicate machinery. It also tends to obscure visibility in confined spaces

Refer to the Firefighting equipment knowledge sheets for information on portable fire extinguishers