There is a shockingly long list of things that are flammable—houses, clothing, furniture, electronic appliances, and oxygen, to name just a few. Any one of these things can burst into flames if it becomes hot enough, and since so many things can catch fire, it can spread rapidly and get out of control. The best thing to do, of course, is to put out the fire while it’s still small—and one of the best ways to do that is to use a fire extinguisher.
How Fire Extinguishers Work
Fire extinguishers—those familiar red canisters which are an essential part of any fire safety system—use substances such as non-flammable gas or water, compressed into a big aerosol can, to neutralize the basic elements that cause a fire: fuel, oxygen, and extreme heat.
The basic parts of a fire extinguisher are the canister itself, which contains both the extinguishing substance and a propellant (usually compressed gas, such as carbon dioxide, inside a cylinder); the nozzle tube, which you aim at the fire; and the lever, which you press to release the extinguishing substance and which is held in place with a pin so the extinguisher doesn’t go off before you need it to.
If and when you do need to use the fire extinguisher, just pull out the pin, aim the nozzle at the base of the fire (it’s more effective if you attack it at its origin), press and hold down the lever, and spray the flames in a sweeping motion. Keep in mind that the fire won’t necessarily stay out once you’ve sprayed it, so keep sweeping until you’re sure it’s out for good.
Remember—don’t try to put out a large fire by yourself! A fire extinguisher should only be used for small household fires in their early stages. If the fire spreads beyond your control, always be ready to get out of the house and call 911.
Types of Fire: Using the Right Fire Extinguisher
Not all fires are alike, and neither are the extinguishing substances used to fight them. Using the wrong fire extinguisher could be useless at best and downright dangerous at worst—so it’s important to know which kind to use.
There are four types, or classes, of fire:
- Class A: Ordinary combustibles (i.e., wood, cloth, paper).
- Class B: Liquid-based fires (i.e., grease, oil, gasoline).
- Class C: Electrical fires.
- Class D: Flammable metals.
Now, since fire is caused by a combination of heat, oxygen, and fuel, the contents of a fire extinguisher are designed to do one of two things: lower the temperature, or keep out the oxygen (getting rid of the fuel is almost impossible, since it’s on fire). Therefore, depending on the nature of the fire, the extinguishing substance will be either a coolant or a smothering agent. The most common substances used in fire extinguishers are:
- Water, which works as a coolant and is excellent for Class A fires. On Class B fires, however, water will only spread the liquid out further—and on Class C fires, it could get you electrocuted.
- A dry chemical foam or powder, such as baking soda or similar compounds, which insulates and smothers the fire. This is good for any fire class.
- Carbon dioxide(CO2), which is heavier than oxygen and therefore works as a smothering agent. Since it cools as it expands, it can also serve as a coolant. Carbon dioxide is ideal for Class B and C fires.
Labeling
Any fire extinguisher you buy should be properly labeled, using either letters or pictures to indicate which type of fire it can be used on. Many fire extinguishers are multi-purpose and are labeled as such. Conversely, fire extinguishers for Class D fires usually contain substances specific to the metals in question, and are therefore specially labeled.
The label on your fire extinguisher should also tell you its range—how many square feet of a particular type of fire it can put out. Keep in mind that most fire extinguishers have a relatively short range—between three and eight feet—as well as a limited amount of extinguishing substance, so make sure you use your fire extinguisher wisely.
Additional Safety Tips
- Make sure your fire extinguisher conforms to national safety standards, and check the pressure gauge regularly (at least once a year) to ensure that it will still be effective when you need it.
- If you do use it, get it recharged by a professional as soon as possible.
- Keep the extinguisher in a cool, accessible place so you can get to it in an emergency—and keep it near an easy escape route, just in case.
Remember, when used responsibly and safely, a good fire extinguisher can save your life.
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