American Chemical Society (ACS) Laboratory Safety Practice Test 2026 – All-in-One Guide to Mastering Lab Safety Procedures!

A "Class-A" fire extinguisher is specifically designed to combat fires that involve ordinary combustibles, which include materials such as wood, paper, cloth, and some plastics. These types of fires result from solid materials that can burn easily and are commonly encountered in both residential and laboratory settings.

Using a Class-A extinguisher for fires involving ordinary combustibles is effective because it typically contains water or other agents that cool the burning material, help extinguish the fire, and prevent re-ignition by absorbing heat. It's important to choose the right type of extinguisher for the fuel source involved in a fire, as using an inappropriate extinguisher can be ineffective or even dangerous. For example, using a Class-A extinguisher on flammable liquids can spread the fire, while using it on electrical equipment could pose a risk of electric shock or further igniting the fire. Thus, understanding that "Class-A" extinguishers are meant for ordinary combustibles is crucial for safe and effective fire response in various environments.