Never fight a fire unless you are certain you have the proper extinguisher and know how to use it. Before using a portable extinguisher, be sure the fire department has been called or is being called and that everyone has left the fire area. Also be sure you have put your back to a safe, unobstructed exit. If the fire begins to spread, leave the area immediately and wait for the fire department.
The extinguisher must be appropriate for the type of fire being fought. If you use the wrong type of extinguisher, you can endanger yourself and make the fire worse. Multipurpose fire extinguishers marked ABC may be used on all three classes of fires. Remember, in some cases, it may be dangerous to just use any type of extinguisher. For instance, pressurized water extinguishers could spread a grease fire.
Class Ratings
Extinguishers are labeled A, B, C or D according to the type of fire they can be used to fight.
| Class |
Usage
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Designator |
| A | Extinguishes fires of ordinary combustibles, such as cloth, wood and paper. The numerical rating for this class of fire extinguisher refers to the amount of water the fire extinguisher holds and the amount of fire it will extinguish. |  |
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| B | Used on fires involving flammable liquids, such as grease, gasoline, oil, kerosene, etc. The numerical rating for this class of fire extinguisher states the approximate number of square feet of a flammable liquid fire that a non-expert person can expect to extinguish. |  |
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| C | Suitable for use on electrically energized fires such as wiring, fuse boxes, machinery, and power cords. This class of fire extinguishers does not have a numerical rating. The presence of the letter "C" indicates that the extinguishing agent is non-conductive. |  |
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| D | Designed for use on flammable metals and are often specific for the type of metal in question. There is no picture designator for Class D extinguishers. These extinguishers generally have no rating nor are they given a multi-purpose rating for use on other types of fires. |  |
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Multiclass Ratings
Many extinguishers available today can be used on different types of fires and will be labeled with more than one designator, e.g. A-B, B-C, or A-B-C. Make sure that if you have a multi-purpose extinguisher it is properly labeled. Multiclass fire extinsuishers will be labeled accordingly as these examples demonstrate:
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Types
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Type
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Usage
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| Dry Chemical | These extinguishers are usually rated for multiple purpose use. They contain an extinguishing agent and use a compressed, non-flammable gas as a propellant. |
| Halon | Contain a gas that interrupts the chemical reaction that takes place when fuels burn. These types of extinguishers are often used to protect valuable electrical equipment since they leave no residue to clean up. Halon extinguishers have a limited range, usually 4 to 6 feet. The initial application of Halon should be made at the base of the fire, even after the flames have been extinguished. |
| Water | These extinguishers contain water and compressed gas and should only be used on Class A (ordinary combustibles) fires. |
| Carbon Dioxide | (CO2) extinguishers are most effective on Class B and C (liquids and electrical) fires. Since the gas disperses quickly, these extinguishers are only effective from 3 to 8 feet. The carbon dioxide is stored as a compressed liquid in the extinguisher; as it expands, it cools the surrounding air. The cooling will often cause ice to form around the “horn” where the gas is expelled from the extinguisher. Since the fire could re-ignite, continue to apply the agent even after the fire appears to be out. |
Usage
Portable fire extinguishers can be effective in fighting small, contained fires. Follow these steps when using a portable fire extinguisher:
When selecting a fire extinguisher, read the label carefully to find out what kinds of fires it will fight. "ABC" or multi-purpose extinguishers are effective on most small fires in the home.
When operating an extinguisher, remember "P.A.S.S. - Pull, Aim, Squeeze, Sweep."
Pull the tab if there is one.
Aim the extinguisher at the base of the fire.
Squeeze the nozzle to activate it.
Sweep it back and forth.
Always keep your back to an exit so that you can escape quickly if the fire does not go out!
Remember, extinguishers are effective only if you know how to use them and only on small, contained fires. For larger fires or fires that are spreading, leave the house at once and call the fire department.
Hazardous Materials Note
When using household hazardous materials, have an extinguisher nearby that has been tested and labeled by an independent testing laboratory for use in fighting Class B (flammable liquid) fires. Do not use an extinguisher labeled for only Class A (paper and ordinary combustible) fires. These extinguishers use water to fight the fire and could make a hazardous materials fire worse. Hazardous materials fires should be fought only with extinguishers using a dry chemical extinguishing agent. These extinguishers will be labeled for use on Class B:C fires or on Class A:B:C (Class C fires involve energized electrical equipment.)