Fire extinguishers are rated by Underwriter’s Laboratories, Inc. according to the types of fires they are designed to put out. There are three classes of fires:
● Class A fires involve paper, wood, cloth, rubber, and some plastics.
● Class B fires involve flammable liquids, such as gasoline, paint thinner, grease, motor oil, and solvents.
● Class C fires are electrical in nature. As a rule, fire extinguishers rated A, B, and C are best for home use.
All fire extinguishers also receive a numeric rating that indicates the size of the fire a particular unit is capable of fighting. For example, a 4-A rating means that the unit will put out twice as much Class A fire as a unit with a 2-A rating. There are no numeric ratings for C class (electrical) fires, because the C rating simply means that the extinguishing agent in the unit is not electrically conductive.
Check the dial gauge on your fire extinguisher monthly. The needle on the gauge indicates whether the unit is operable or in need of recharging. When required, have the unit recharged by a qualified professional–you can usually find these professionals listed under Fire Extinguishers in your Yellow Pages. Recharging is required after every use, no matter how brief.
Handled correctly, even a small 5 lb. dry chemical extinguisher can put out a fairly large fire. View this video for a demonstration.