A fire extinguisher is an important tool for keeping your home safe from the danger of a fire. There are many different types of fire extinguishers, each designed for a specific type of fire. Knowing which type of fire extinguisher to use can save lives and prevent hefty property damage.
A basic fire extinguisher is a pressurised container holding a fire-suppressant agent. When you pull the pin on the handle, it activates a spring-loaded valve threaded into the pressure cylinder. This allows the pressure of stored gas to push the agent out through a nozzle.
There are four common fire extinguishers: water, foam, dry powder and carbon dioxide. Each is designed to be used on a certain class of fire, and carries a numerical rating to indicate the amount of fire it can suppress.
Water extinguishers are used on Class A fires, which are ordinary combustible materials such as paper, wood, cloth and most plastics. Water also cools the fire and removes heat, slowing or stopping its spread. This is the best extinguisher to use on a small kitchen fire, as it can be easily operated and won’t contaminate food.
Foam extinguishers have a distinctive white appearance and are typically used on Class B and Class C fires, which involve flammable liquids such as gasoline, kerosene, oils and grease. The insulating property of the foam smothers the fire by cutting off its oxygen supply, and it also absorbs heat to further reduce the fire’s temperature. Foam is also useful on electrical fires, as it does not conduct electricity, avoiding the potential shock hazard to you.
Dry Powder Extinguishers
Dry chemical extinguishers contain a powdered agent such as sodium bicarbonate (normal baking soda), potassium bicarbonate, or monoammonium phosphate. When discharged on a fire, the powder forms a coating over the fuel to cut off its supply of oxygen and smother it. This is the most popular type of fire extinguisher.
Carbon Dioxide Extinguishers
These contain pure pressurised carbon dioxide gas, which does not leave any residue and is a good choice for electrical fires, such as those involving computers or large electric equipment. The low pressure and short range of CO2 make it effective for a much smaller area than other extinguishers. It’s also practical for offices because it doesn’t contaminate delicate and expensive electronic equipment.
Electric Fire Extinguishers
These fire extinguishers use an electrically nonconductive solvent to interrupt the flow of current, thereby preventing the fire from starting or spreading. The nozzle on an electric fire extinguisher is designed to deliver a spray rather than a jet, to cover a larger surface area more quickly.
If you decide to use a fire extinguisher, always remember that the best way to prevent serious injury or death is to escape the fire. Only use an extinguisher if: The fire department has been notified, there is a clear exit from the fire, you know what is burning, you have the correct type of fire extinguisher for that material and you’ve been trained on proper use within the past year.