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Tech Essentials: Fire Extinquishers
Tech Essentials: Fire Extinquishers

Fire extinguishers are a vital component to any facilities safety plan. They are ideal for putting out and controlling fires caused by flammable liquids, combustibles, cooking, electrical malfunctions and other incendiary situations. Find out about several types of fire extinguishers and which environments they are best used in as well as their UL ratings.

Fire Extinguisher Diagram

Fire Extinguisher Types:

Carbon Dioxide Extinguisher Image

Carbon Dioxide Extinguishers are filled with highly pressurized carbon dioxide. It dissipates quickly and without residue. It’s ideal for computer rooms, cleanrooms and electronic motors. Carbon dioxide is not effective with Class A fires.
UL Rating: Class B and C.

Dry Chemical Extinguishers

Dry Chemical Extinguishers are filled with mono-ammonium phosphate dry chemical, sodium bicarbonate or potassium bicarbonate.
UL Rating: Class A, B and C.

Essential Tip:
Rechargeable Extinguishers can be reused after service and should be recharged by an authorized professional.

Halotron Extinguishers

Halotron Extinguishers are filled hydrochlorofluorocarbon (HCFC) blends of chlorine, fluorine, carbon and hydrogen. It leaves no residue, is ozone friendly and will not cause thermal shock to electrical equipment.
UL Rating: Class A, B and C.

Water Extinguishers are filled with air-pressurized water. They do not leave a chemical residue behind after use.
UL Rating: Class A.

Wet Chemical Extinguishers

Wet Chemical Extinguishers are filled with potassium acetate, carbonate or citrate. It is ideal for use on cooking media including vegetable or animal oils and fats. UL Rating: Class K.

UL Ratings Defined Extinguishers

UL Ratings Defined:

UL Fire Extinguisher Ratings indicate fire-fighting capabilities as tested by Underwriters Laboratories, Inc. UL ratings are identified by a number, followed by class rating letter(s). The first number set in the rating is multiplied by 1.25, indicating the extinguishing agent in gallons. The second number set applies to the square feet the extinguisher covers.

The ratings can be seen on each extinguisher with a labeled number, followed by a letter. For example, "3-A," the number (3) indicates the relative power against a certain class (A) of fire (for class information please see below). The 3-A has triple the power against a common combustible fire compared to one rated 1-A. Class C fire extinguishers are not labeled with a relative power rating because these fires are a combination of a Class A and Class B with live electrical equipment.


UL Rating Key:

Class A extinguishers are used for fires that involve common combustibles such as wood, paper, cloth, rubber, trash and plastics. These fires are common in a typical home or commercial settings, and can occur anywhere these types of materials are found.

Class B extinguishers are used for fires that involve flammable liquids, gases, solvents, oil, gasoline, paint, lacquers, tars and other synthetic or oil-based products. Class B fires often spread rapidly and can even reflash after the flames are extinguished.

Class C extinguishers are used for fires that involve electrical equipment such as computers, wiring, controls, motors, data processing panels or appliances. They can be caused by a spark, power surge or short circuit.

Class D extinguishers are used for fires that involve combustible metals such as magnesium, lithium and sodium. Combustible metal fires, which are unique to industrial hazards, require special dry powder agents.

Class K extinguishers are used for fires that involve fires combustible cooking media such as oils and grease commonly found in commercial kitchens. The new cooking media formulations used to form commercial food preparations require a special wet chemical extinguishing agent that is specially suited for extinguishing and suppressing these extremely hot fires that have the ability to reflash.

UL Ratings Key Extinguishers