How to Use a Fire Extinguisher

Fire extinguishers can be the difference between control and chaos when a small fire breaks out in the workplace. By having the right types of extinguishers on hand and knowing how to use them, employees can take action and stop the fire from spreading, reducing property damage and avoiding employee injury.

A fire extinguisher is a pressurized container of chemical or other agent that puts out a fire by disrupting its chemical chain reaction. They come in various forms, including dry chemicals, gases and foams. Most fire extinguishers have usage instructions printed on them. However, employees may not have time to read these during a fire emergency, especially when every second counts. Fortunately, there is a simple acronym that employees can remember and follow: P.A.S.S.

Pull the pin or break the seal to discharge the fire extinguisher. Aim low, pointing the nozzle at the base of the fire. Squeeze the handle, releasing the extinguishing agent. Sweep the nozzle from side to side, covering the entire firebase until it appears to be out. Watch the area and if it re-ignites, repeat the process.

Class A fires are fueled by solid combustibles such as wood, paper and cloth. Class B fires are fueled by flammable liquids such as oil and gasoline. Class C fires are fueled by electrical equipment such as fuse boxes and appliances. Class K fires are fueled by cooking oils and fats.

The most common type of fire extinguisher is a dry chemical. Developed in 1928, dry chemical fire extinguishers consisted of sodium bicarbonate that was treated with chemicals to make it free-flowing and moisture resistant. They were not widely used until 1949, when Ansul developed a portable pressurized extinguisher using an external CO2 cartridge to discharge the dry powder. Graphite and other manually applied dry agents also existed at that time.

In the 1960s, gaseous fire extinguishers were introduced. Carbon tetrachloride (Cl2), methyl bromide (MeBr) and halon were the most popular, although these were all eventually banned because of their toxic effects on people. In the 1980s, liquefied propane gas (LPG) and ammonia were introduced as more effective alternatives.

Aqueous film-forming foam (AFFF or FFFP) fire extinguishers are designed to be used on both Class A and Class B fires by discharging a liquid that engulfs the flames and suffocates them. They are also available in a variety of sizes.

When using a fire extinguisher, make sure to keep it as close to the fire as possible and not blocking the escape path. Ensure that the pressure is at its recommended level. Check and shake dry chemical extinguishers at least once a month to prevent the powder from settling or packing. Water spray and foam extinguishers should be shaken as well to remove any buildup of contaminants on the nozzles or hoses.