Which fire-fighting method is commonly used for class B fires?

The correct answer is foam suppression, which is the most effective method for combating Class B fires. Class B fires involve flammable liquids such as gasoline, oil, and grease. These types of fires require special extinguishing agents that can form a barrier between the fuel and the fire.

Foam suppression works by creating a blanket of foam that smothers the flames, effectively cutting off the oxygen supply necessary for combustion and preventing re-ignition. This method is particularly advantageous in scenarios where flammable liquids are involved, as the foam can also help to suppress vapors that could lead to further fire spread.

While other extinguishing agents like dry chemical agents or carbon dioxide can be useful for various types of fires, they may not provide the same level of protection against re-ignition that foam suppression does. Water extinguishers are not suitable for Class B fires as they can spread the burning liquid and worsen the fire situation. Hence, foam suppression is the preferred method for effectively managing Class B fires.