A stored-pressure water extinguisher should be used to attack which class of fire?

A stored-pressure water extinguisher should be used to attack which class of fire?

• A. Class D
• B. Class A
• C. Class B
• D. Class C

Answer: (B)

Stored-pressure water extinguishers work by absorbing a large amount of heat and cooling the burning material to below its ignition temperature. This cooling effect is most effective on ordinary combustibles—wood, paper, cloth, and similar materials—so they are used on Class A fires. The water’s heat-absorbing action interrupts the combustion process and helps prevent reignition. They’re not suitable for other fire types: for flammable liquids (Class B), water can spread the liquid and worsen the fire; for electrical fires (Class C), water conducts electricity and poses a shock hazard; and for metal fires (Class D), water is ineffective and can react with some metals. So the stored-pressure water extinguisher is best used for Class A fires.

Stored-pressure water extinguishers work by absorbing a large amount of heat and cooling the burning material to below its ignition temperature. This cooling effect is most effective on ordinary combustibles—wood, paper, cloth, and similar materials—so they are used on Class A fires. The water’s heat-absorbing action interrupts the combustion process and helps prevent reignition.

They’re not suitable for other fire types: for flammable liquids (Class B), water can spread the liquid and worsen the fire; for electrical fires (Class C), water conducts electricity and poses a shock hazard; and for metal fires (Class D), water is ineffective and can react with some metals. So the stored-pressure water extinguisher is best used for Class A fires.