Fire extinguisher

Fire Extinguisher

A fire extinguisher is an active fire protection device 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, or otherwise requires the expertise of a fire department.

A typical ABC fire extinguisher

Types of Fire Extinguishers

Fire extinguishers are classified by the type of fire they are designed to extinguish. The main types include:

Class A

Class A extinguishers are used for ordinary combustibles such as wood, paper, and cloth. These extinguishers typically use water or foam to cool the burning material below its ignition temperature.

Class B

Class B extinguishers are used for flammable liquids like gasoline, oil, and grease. These extinguishers work by smothering the fire, cutting off the oxygen supply.

Class C

Class C extinguishers are used for electrical fires. They contain non-conductive agents such as carbon dioxide or dry chemical powders to extinguish the fire without conducting electricity.

Class D

Class D extinguishers are used for combustible metals such as magnesium, titanium, and sodium. These extinguishers use a dry powder to separate the fuel from oxygen or to remove the heat element of the fire triangle.

Class K

Class K extinguishers are used for kitchen fires involving cooking oils and fats. They use a wet chemical agent to cool and smother the fire.

A wheeled fire extinguisher for industrial use

Operation

Most fire extinguishers operate using the PASS technique:

• Pull the pin to break the tamper seal.
• Aim low, pointing the extinguisher nozzle at the base of the fire.
• Squeeze the handle to release the extinguishing agent.
• Sweep from side to side at the base of the fire until it appears to be out.

History

The first fire extinguisher was invented by George William Manby in 1818. It consisted of a copper vessel of three gallons of pearl ash (potassium carbonate) solution under compressed air pressure.

An early fire grenade used for fire suppression

Modern Developments

Modern fire extinguishers have evolved to include various types of extinguishing agents, such as dry chemical, foam, and carbon dioxide. These agents are chosen based on the type of fire they are designed to combat.

Cutaway view of fire extinguishers showing internal components

Maintenance

Fire extinguishers require regular maintenance to ensure they are in working order. This includes checking the pressure gauge, ensuring the nozzle is clear, and verifying the expiration date of the extinguishing agent.

Related Pages

• Fire safety
• Fire department
• Fire triangle
• Fire suppression system

A vintage Comet fire extinguisher

See Also

• Fire blanket
• Smoke detector
• Sprinkler system

A soda-acid fire extinguisher

External Links

• National Fire Protection Association
• Occupational Safety and Health Administration