All About Fire Extinguishers

When buying a fire extinguisher, you must know where the extinguisher is likely to be used and what kind of fire may be involved... Class A, B, C or D fire.

• Class A fires - the most common type, are ordinary combustibles such as wood, paper, cloth, rubber and many plastics.
• Class B fires - flammable liquids, gases and greases.
• Class C fires - energized electrical equipment or wiring where the electric non-conductivity of the extinguishing agent is important. However, when the equipment or wiring is de-energized, remaining combustion is Class A or B and extinguishers for those fires may be safely used.
• Class D fires - combustible metals such as magnesium, titanium, zirconium, sodium and potassium. You will not often be called upon to supply extinguishers for Class D fires.

Extinguisher Ratings

The most reliable guide to the fire-killing ability of an extinguisher is the rating assigned it by Underwriters' Laboratories, Inc., which appears on the equipment nameplate. Size alone is not a satisfactory measure of extinguisher effectiveness.

Each rating consists of one or more numbers and letters. The letter tells the class of fire the extinguishing agent is designed for. The number indicates approximate relative extinguishing potential. For example, an extinguisher rated 4A is capable of putting out twice as much burning material as one rated 2A. (The "A" means Class A.)

The number used for Class B extinguishers also shows the square-foot area of a deep-layer flammable liquid fire which a trained operator can put out. Class C extinguishers have no "C" commercial rating.

Types of Extinguishers

Water-type extinguisher - Class A fires. Includes water, antifreeze, soda-acid, wetting agent and loaded-stream extinguishers.

Carbon dioxide extinguisher - Class B and C fires. Has limited range and is affected by draft and wind.

Dry-chemical extinguisher - Class B and C fires. Includes sodium and potassium bicarbonate base agents. Dry-chemical extinguishers marked general-purpose or multipurpose can be used on Class A, B and C fires.

Foam extinguisher - Class A and B fires. Not effective on flammable liquids and gases escaping under pressure.

Halon extinguisher - Recommended for Class B and C fires but not for Class A fires in paper, wood and cloth. Halon extinguishers are lighter, more compact and more effective than carbon dioxide and will not stop an engine from running. Halon is colorless, odorless and will not damage engine parts, electrical systems or other sensitive equipment and leaves no residue.

Halon 1211 is a gas found in small hand extinguishers and pressurized with nitrogen. Halon 1301 is a vapor form, somewhat less toxic and found in fixed commercial and marine applications. Halon extinguishers are the most expensive of the types listed here.

A number of extinguishers are labeled "all purpose" or "multipurpose." They use a fine powder of ammonium phosphate that is effective against all types of fire. They are a logical choice, but not as efficient at extinguishing as the rated units can be for specific types of fires.

Extinguisher Placement

One fire extinguisher is not enough protection for a home. Four would provide good protection in a three-bedroom home with a basement and garage-one near the bedrooms, one for the basement, one for the garage and one for the kitchen.

It is recommended that multipurpose, dry-chemical fire extinguisher units be used throughout a house as protection against all types of fires.

Do not mount a fire extinguisher too close to a place fire might occur. For example: In the kitchen, do not mount it close to the stove. In the basement, the best place is at the top of the stairs unless circumstances demand that it be near a workshop area. You should not risk reaching into a fire or going into a burning area to get a fire extinguisher.

Also use caution to fight only minor fires. In case of a serious blaze, all persons should immediately leave the house. Notify the fire department from a neighbor's home or an alarm box.

DISCLAIMER: Check your state and local codes before starting any project. Follow all safety precautions. Every effort has been made to ensure the accuracy and safety of the information in this document. Neither NRHA, any contributor nor Aubuchon Hardware can be held responsible for damages or injuries resulting from the use of the information in this document.

National Retail Hardware Association

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