How to Use a Fire Extinguisher

Fire extinguishers are used to control small fires by removing oxygen and blocking the chemical reaction that causes the fire to burn. They come in many different shapes and sizes and can be found in businesses, schools, homes and some motor vehicles.

Fires can happen at any time, and it’s important to be prepared for them. Having the proper fire extinguisher in an accessible location can make the difference between a minor incident and a major disaster. A fire extinguisher should be mounted in a place where it can easily be reached and located away from any heat sources that could limit its use or cause damage. If an extinguisher is ever discharged or if the pin is pulled, it must be recharged immediately.

The acronym PASS is a simple way to remember the steps to using a fire extinguisher: Pull, Aim, Squeeze, Sweep. The first step is to pull the pin at the top of the extinguisher, which breaks a seal and releases the pressurized fire-extinguishing agent inside. Aim low, pointing the nozzle or hose at the base of the fire rather than directly at the flames. The last step is to squeeze the handle, which depresses a lever or button that activates the fire-extinguishing chemical.

Water extinguishers are the easiest to use and maintain. They contain a spray or jet of water that cools the fire, eliminating the heat and stopping the fire’s chemical reaction. They are effective on Class A fires (paper, cloth, wood), class B fires involving flammable liquids or gasses and class C fires involving energized electrical equipment.

Wet chemical fire extinguishers use a combination of sodium bicarbonate and silica gel to fight pyrophoric fuel fires (that ignite on contact with air). They also interrupt the chain reaction that allows combustible fuel to continue burning. This type of fire extinguisher is usually blue or red in color and can be found in offices, schools, retail businesses, hotels, restaurants and warehouses.

Cartridge-operated dry chemicals use a chemical called monoammonium phosphate, which is similar to baking soda but more effective on flammable liquids. They can be used on class B and class C fires, and are a good choice where piped water may not be available or freezing conditions are expected.

Foam fire extinguishers form a frothy blanket that covers the fuel and blocks the oxygen that fuel needs to burn. They can be used on fuel and electrical fires and are usually red in color.

Be sure to check the fire extinguisher’s pressure gauge regularly and recharge it immediately after each use. A faulty pressure gauge could rupture the cartridge, causing it to leak and lose its effectiveness.

If you’re unable to put out the fire with your fire extinguisher, call the fire department right away. The fire department will be able to survey the area and ensure that there are no lingering sparks or fumes that could re-ignite. Wait until the fire department clears your home before going back in, and be sure to follow their instructions about evacuating.