A fire extinguisher is a hand-held device used to put out small flames by directing a substance onto the fire that cools it, deprives it of oxygen or interferes with its chemical reactions. Fire extinguishers can be found in many homes, businesses and public buildings. A fire that is not controlled can quickly grow out of control, and the hazard to people and property is enormous. Having a fire extinguisher readily available can give you the time needed to escape or to call the fire department.
Before using a fire extinguisher, it’s important to remember several safety precautions. Fires double in size every 60 seconds, so it’s important to act quickly. It is also important to determine if you have the right type of fire extinguisher for the blaze and that it is in good working order. Lastly, make sure you can reach the fire extinguisher and that nothing is standing in your way of getting it to the fire.
The first step in fire extinguisher use is to activate the pressure gauge and check for adequate pressure. Then, read the manufacturer’s instructions for proper usage. Fire extinguishers are rated according to the type of fire they can combat, from Class A (wood, paper and ordinary plastics) to Class D (electrical equipment and highly reactive metals).
There are essentially two kinds of fire extinguishers: stored pressure and cartridge-operated. The former has a copper cylinder with an internal carbon dioxide cartridge that is operated by turning a wheel valve on top and squeezing a handle on the end of a hose to discharge the agent. A handle also controls the direction of the agent spray. These extinguishers are generally easy to use and require little maintenance.
Cartridge-operated extinguishers are available as dry chemical foam or powder (classes A and B) and wet chemical (classes C and D) types in the United States. The latter uses a chemical like sodium bicarbonate, potassium bicarbonate or monoammonium phosphate that is similar to baking soda and is much easier to find in home extinguishers. The chemical is sprayed over the fire and then allowed to penetrate it and smother it.
A few decades ago, the halon gas family was introduced for use in hand-held fire extinguishers. Halon is a colorless, odorless and tasteless gas that inhibits the chemical reaction of the fire. It was effective in fighting fires of most types, including classes A and B, but was prohibited for new production under the Montreal Protocol after 1994 due to its detrimental effect on the ozone layer.
When using a fire extinguisher, stand about 6-8 feet away from the fire and position yourself with the nozzle of the extinguisher at the base of the flames. Remember the acronym PASS: P = Pull pin, Aim low, Squeeze the handle and Sweep from side to side. Remember that a fire will likely return to life after you have used an extinguisher, so be ready to repeat the steps until the fire is out. If the fire does reappear, evacuate the area and call the fire department.