Fire Extinguishers
Fire Extinguishers
HOW TO USE A FIRE EXTINGUISHER
Remember the acronym "P.A.S.S."
| P | ......Pull
the Pin. |
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|---|---|---|
| A | ......Aim the extinguisher nozzle at the base of the flames. | |
| S | ......Squeeze trigger while holding the extinguisher upright. | |
| S | ......Sweep
the extinguisher from side to side, covering the area of the fire with the extinguishing agent |
HOW TO IDENTIFY THE PROPER EXTINGUISHER
The color, size, contents, and nozzle of fire extinguishers vary according to their intended purpose.
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Pressurized water extinguishers are usually silver (chrome metal) in color, have a flat bottom, long hose, and are quite large (2 1/2 gallons). Rated for Class A fires only. |
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Multi-purpose dry powder extinguishers are the most common of all types. They are almost always red (small kitchen units are sometimes white) and have either a long, narrow hose or no hose at all (only a short nozzle). These extinguishers are very light (5-25 lbs.). Rated for Class A, B, or C fires. |
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Ordinary dry powder extinguishers may look like the multi-purpose extinguishers or may appear quite different. Refillable dry powder extinguishers have a screw-on top cap and a covered, side-mounted gas cylinder with a hose. These extinguishers are very light (5-25 lbs.). Rated for Class B, or C fires. |
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Carbon dioxide extinguishers are generally red, have a large "horn" at the end of the hose, and are very heavy (15-85 lbs.). These are all high-pressure cylinders which should not be dropped. CO2 cylinders do NOT have a pressure gauge - they must be weighed to determine the amount of contents. Rated for Class B and C fires. |
To make selection of the proper extinguisher easier, all fire extinguishers carry a letter rating (A-D) on the faceplate. These letters indicate which class of fire the extinguisher is capable of extinguishing. It is important to choose correctly as using the wrong extinguisher can make the fire worse. Some carry multiple ratings such as AB, BC, or ABC. These extinguishers are capable of putting out more than one class of fire.
CLASSIFICATION OF FIRE
Fires are classified by the type of fuel involved in the chemical reaction. There are four classes of fires.
CLASS
A
MATERIAL: Ordinary combustibles or fibrous material such as wood, paper, cloth, rubber and some plastics (anything that will leave an ash)
PREVENTION: Keep storage and work areas free of trash. Avoid placing materials next to possible heat sources.
EXTINGUISHMENT: Extinguish ordinary combustibles by cooling the material below its ignition temperature and soaking the fibers to prevent re-ignition. Use pressurized water, foam, or multipurpose (ABC-rated) dry chemical extinguishers. DO NOT USE carbon dioxide or BC-rated dry chemical extinguishers on Class A fires.
CLASS
B
MATERIAL: Flammable or combustible liquids such as gasoline, kerosene, oil-base paint, paint thinners and grease.
PREVENTION: Don't refuel equipment while the engine is hot or in a confined space. Keep all flammable liquids in tightly sealed, spill-proof containers. Use flammable liquids only in well ventilated areas.
EXTINGUISHMENT: Extinguish flammable liquids by removing oxygen, preventing the vapors from reaching the ignition source, or inhibiting the chemical chain reaction. Use multi-purpose or ordinary dry chemical and carbon dioxide extinguishers on Class B fires.
CLASS
C
MATERIAL: Energized electrical equipment such as appliances, switches, panel boxes and circuits.
PREVENTION: Replace electrical items with worn insulation or broken fittings. Don't misuse fuses - never replace a fuse with a higher rated unit. Don't overload wall outlets.
EXTINGUISHMENT: Extinguish energized electrical equipment by using an agent which is not capable of conducting electricity. Use multi-purpose or ordinary dry chemical and carbon dioxide extinguishers on Class C fires. DO NOT USE water extinguishers as water is a conductor.
CLASS
D
MATERIALS: Certain combustible metals such as magnesium, titanium, potassium and sodium. These metals burn at high temperatures and give off sufficient oxygen to support combustion.
PREVENTION: Pure metals such as potassium react violently or even explosively with water. All reactive metals should be stored in sealed containers in a non-reactive liquid to prevent decay (surface oxidation) from contact with moisture in the air.
EXTINGUISHMENT: Extinguish combustible metals by covering it with a dry powder or sand. DO NOT USE water or other moist agent to extinguish a Class D fire as it will cause further reactions. Class D extinguishing agents (dry powder) are commonly available in buckets or boxes.
SPECIAL NOTES
Multi-purpose (ABC rated) chemical extinguishers leave a residue that can seriously harm sensitive equipment such as computers. Because of this, CO2 extinguishers are preferred in these instances because they leave very little residue.
Extinguishers generally will not hold their charge after being used, even if the use was minimal. Dry agents also tend to clog the hose lines after use. For these reasons, ALL extinguishers should be refilled and inspected after ANY use.
Water and multi-purpose dry chemical extinguishers have gauges indicating the pressure inside the extinguisher. The needle should be within the green area which is generally 100-175 lbs.
