What is the difference between class A and class B fires?

The distinction between Class A and Class B fires is fundamentally based on the types of materials that are burning. Class A fires are fueled by ordinary combustible materials such as wood, paper, cloth, and some plastics. These are the types of fires that one would commonly encounter in everyday situations. To extinguish Class A fires, methods like water and certain fire retardants are effective because these materials generally undergo combustion through the release of water vapor or heat.

On the other hand, Class B fires involve flammable liquids and gases, such as gasoline, oil, paint, and solvents. These materials are more volatile and can spread rapidly, often making them more dangerous compared to Class A fires. Extinguishing Class B fires typically requires specialized firefighting agents like foam, dry chemicals, or CO2, which do not react with the burning liquids.

Understanding this classification is crucial for firefighters, as it informs them about the appropriate methods and materials to use for firefighting, ensuring safety and effectiveness in different fire scenarios.