How to Maintain a Fire Extinguisher

Fire extinguishers are used to suppress small fires and keep them from spreading before emergency response personnel arrive. They are often placed in areas where fires are most likely to occur, such as the kitchen and garage. A fire extinguisher must be maintained regularly to ensure it is ready for use when required. Failure to do so can result in an empty or corroded extinguisher that will not discharge when needed and can potentially be harmful.

There are several types of hand-held fire extinguishers: carbon dioxide, dry chemical and foam water. Each type is suitable for a different group of fuels.

Carbon dioxide fire extinguishers discharge a highly pressurized gas that excludes oxygen from the area surrounding the fire, stopping the chain reaction that sustains it. They are most effective on class A fires, such as wood and paper.

Dry chemical fire extinguishers contain powdered agents that separate the fuel and oxygen, cutting off the fire’s supply of energy. These agents can also decontaminate the scene of the fire by dispersing fine particles that cling to clothing and equipment. Monoammonium phosphate (also known as ABC dry chemical or multipurpose) is the most common agent found in these types of fire extinguishers.

Foam water fire extinguishers are designed to stop class B and class C fires by forming an air-excluding foam blanket over the burning material, smothering it. Foam is composed of water vapor and a soapy substance that coats the surface of the flame, cooling it below its ignition temperature. These extinguishers are typically black in color and rated A:K or A:C.

In the past, AFFF (aqueous film forming foam) was a popular choice for foam water extinguishers, but it has since been banned from production and sale in most countries due to its contribution to ozone depletion. Previously produced as a solid charge model, AFFF is now only available in pre-mixed form.

When using a fire extinguisher, remember to aim for the base of the flame and sweep side to side until the fire is out. Then, wipe down the handle and nozzle to remove any residue and check for a pressure gauge to ensure that it is still fully charged. If it is not, the operator should replace the pin seal and recharge the unit as instructed in the user’s manual. Most countries require fire extinguishers to be regularly serviced by a trained person. This maintenance prevents the extinguisher from being inoperable when it is needed and protects against corroded hoses that can rupture under high pressure.