Occupational Safety and Health Administration (OSHA) SLC Practice Exam

Which type of fire extinguisher contains pressurized water and is used on combustible fires?

1. Fire Extinguisher A

2. Fire Extinguisher B

3. Fire Extinguisher C

4. Fire Extinguisher ABC

The correct answer is: Fire Extinguisher A

The correct answer is based on the fact that Fire Extinguisher A is specifically designed for use on Class A fires, which involve ordinary combustibles such as wood, paper, and cloth. These types of fires are best extinguished with water, which cools the burning materials and eliminates the heat element of the fire triangle. Fire Extinguisher A contains pressurized water that effectively penetrates and cools the fuels of Class A fires, helping to stop the fire from spreading. Using water on other classes of fires, such as those involving flammable liquids or electrical equipment, would be inappropriate and could exacerbate the situation, making it vital to understand the specific fire types that different extinguishers are designed for. Fire Extinguisher B, for example, is intended for use on flammable liquids, while Fire Extinguisher C is suitable for electrical fires. Fire Extinguisher ABC covers Class A, B, and C fires, providing versatility but still does not exclusively analyze the water component focused on Class A fires. This specificity is why Fire Extinguisher A is recognized as the type that contains pressurized water for combating combustible fires effectively.