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Fire Extinguishers

In the event of a fire, the correct use of a portable fire extinguisher could mean the difference between suffering a minor loss or a major one. There are several things to consider when using the fire extinguishers. For instance, you must know the class of fire involved and the correct type of fire extinguisher to use.

Classes of Fires and Fire Extinguishers

Class A: Involves ordinary combustibles such as paper, wood, rubber or plastics. The most common extinguishing material is pressurized water, foam or multipurpose dry chemical.

Class B: Flammable liquids, grease or gases are covered under this category. Common extinguishing materials are foam, carbon dioxide or dry chemical. These fires can be harder to extinguish and should be approached with extreme caution.

Class C: Electrical fires involving energized electrical equipment are class C fires. Carbon dioxide, dry chemical, and clean agent extinguishers are commonly used. DO NOT use water extinguishers on energized electrical equipment. *Multipurpose dry chemical extinguishers leave a residue that can be harmful to sensitive electronic and computer equipment. Carbon dioxide or Clean Agent extinguishers are preferred in these instances because they leave very little reside.

Class D: burning materials include combustible metals such as magnesium, titanium, potassium and sodium. Special extinguishing agents, approved by recognized testing laboratories, are needed when working with these metals. In most cases, they absorb the heat from the material, cooling it below its ignition temperature.


All fire extinguishers are labeled with standard symbols of the classes of fires they can put out. A red slash through any of the symbols tell you the extinguisher cannot be used on that class of fire. A missing symbol tells you only that the extinguisher has not been tested for use on a given class of fire.

Nearly all fire extinguishers at SMC are Class ABC, which means they can be used on any Class A, B, or C fire. Class D fires are rare and would not be expected to occur on SMC property.


Fire Extinguisher

Ready the Extinguisher

Quickly but carefully, remove the extinguisher from its mounting bracket. It may be heavy, so use caution when lifting it. Stand at least five feet away from the fire. Prepare to properly release the extinguishing agent. Do not squeeze the handle before you have aimed the nozzle properly as valuable time and extinguishing agent will be wasted. Most extinguishers only allow about 10 seconds of extinguishing material.

Remember P-A-S-S When Using an Extinguisher

P – Pull. Pull the locking pin that secures the handle before using the fire extinguisher.
A – Aim. Aim the fire extinguisher nozzle at the base of the fire, not at the flames or smoke.
S – Squeeze. Squeeze the handle to operate and discharge. Do not be startled by the noise or velocity of the agent as it is released.
S – Sweep. Sweep the fire extinguisher back and forth at the base of the fire until it is completely out. Be alert for re-ignition.

Once the fire is out, carefully back away from the scene and watch for re-ignition. If you cannot extinguish the blaze, your extinguisher runs out of agent, the fire threatens your escape path, or the fire gets out of control, evacuate the area immediately.