Which class of portable fire extinguishers uses water as an extinguishing agent?

The correct answer is Class A, as this class of portable fire extinguishers is specifically designed to combat fires involving ordinary combustible materials such as wood, paper, cloth, and some plastics. Water serves as an effective extinguishing agent for these types of fires because it cools the burning material and reduces the temperature below the ignition point.

Class A extinguishers are typically marked with a “triangle” symbol, which helps identify their use for common fire hazards. The use of water in this class is beneficial because it not only cools the flames but can also help to soak the materials, thus preventing re-ignition. Understanding the classification of extinguishers is crucial for effective fire safety management, as using the wrong type of extinguisher for a specific fire can lead to dangerous situations.

Other classes of extinguishers are designed for different types of fires. For example, Class B extinguishers are used for flammable liquids, Class C for electrical fires, and Class D for combustible metals, each requiring specialized agents to effectively suppress those specific hazards.