Fire Extinguishers

Part No.



2-1/2 lb. 10B:C Extinguisher w/ Zytel Valve & Nylon Strap


ABC’s of Fire Extinguishers

There are basically four different types or classes of fire extinguishers, each of which extinguishes specific types of fire. Class A, Class B, Class C and Class D

Our industry primary uses extinguishers available that 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

Class A Extinguishers will put out fires in ordinary combustibles, such as 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.


Class B Extinguishers should be used on fires involving flammable liquids, such as grease, gasoline, oil, 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.


Class C Extinguishers are suitable for use on electrically energized fires. 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.


Dry Chemical extinguishers are usually rated for multiple purpose use. They contain an extinguishing agent and use a compressed, non-flammable gas as a propellant.

Multipurpose Dry Chemical for Class A, B, and C Fires. The monoammonium phosphate agent is inexpensive and electrically nonconductive but leaves a powdery residue that can damage equipment. It's not good for hidden fires.

Dry Chemical for Class B and C Fires. The potassium bicarbonate and sodium bicarbonate agents are extremely effective against Class B fires and are electrically nonconductive. They produce no toxic effects and cleanup is accomplished with a vacuum cleaner or broom and dustpan

How are Extinguishers Rated?

The fire rating of an extinguisher provides a guide to its extinguishing ability. As a result of fire testing by Underwriters' Laboratories, Inc., fire extinguishers carry a classification on their nameplates that consists of a numeral followed by a letter. The numeral indicates the approximate relative fire extinguishing capacity of the extinguisher on the class of fire, which is identified by a letter.

For example, a 4-A extinguisher can put out approximately twice as much fire as a 2-A extinguisher, and a 20-B:C extinguisher can put out approximately twice as much flammable liquid fire as a 10-B:C extinguisher.

For Class B extinguishers, the numeric rating also indicates the fire suppression capacity of the extinguisher when used by an inexperienced operator. That is, a novice can put out a fire encompassing 10 sq. ft. (.9 m2) with a 10-B:C extinguisher and a 20 sq. ft. (1.8 m2) fire with a 20-B:C extinguisher. The fire suppression capacity is related to the experience of the operator. For example, an experienced operator can put out a fire encompassing 25 sq. ft. (2.3 m2) with a 10-B:C extinguisher and 50 sq. ft. (4.6 m2) with a 20-B:C extinguisher.

Class C extinguishers carry only the symbol and have no numerical rating because such fires are essentially Class A or Class B fires involving energized electrical equipment.

DOT requirements:

Each State DOT has its own special rules regarding fire extinguishers requirements for commercial motor vehicle. Refuse, Log Trucks, Flammable Liquids often require additional protection. Operators should check their states DOT for specifics. The basic guide line, provided by the United States Department of Transportation – Part 393- Parts and Accessories Necessary for Safe Operation


Commercial motor vehicles must carry the following emergency equipment:

  • Fire extinguisher (not required for driveaway-towaway operations)

  • Spare fuses

  • Warning devices for stopped vehicles

Fire extinguishers must be securely mounted and readily accessible for use. Each extinguisher must have a gauge or other indicator that shows whether the extinguisher is fully charged, and a label showing its Underwriters' Laboratories (UL) rating.

The fire extinguisher's must meet one of the following standards:

  • One extinguisher with a UL rating of 5 B:C or more or

  • Two extinguishers each with a UL rating of 4 B:C or more.

  • One extinguisher with a UL rating of 10 B:C, if the vehicle is transporting placardable quantities of hazardous material.