Which type of foam is used to extinguish Class B fires involving hydrocarbons?

The correct choice for extinguishing Class B fires involving hydrocarbons is protein foams. Protein foams are specifically formulated to combat flammable liquid fires, particularly those involving hydrocarbons such as gasoline, oil, and other petroleum products.

The effectiveness of protein foams comes from their unique composition, which includes hydrolyzed proteins that create a thick, stable blanket on the surface of the burning liquid. This blanket not only suppresses the fire by cutting off the oxygen supply but also prevents vapor release, which can lead to re-ignition.

In contrast, synthetic foams and fluoroprotein foams may also be used for Class B fires, but they have different properties and applications. Synthetic foams typically contain various synthetic surfactants and can be very effective against both polar and non-polar liquids, while fluoroprotein foams offer some advantages in fighting fires involving flammable liquids but may not be the first choice for hydrocarbons specifically. Class A foams, on the other hand, are primarily designed for combating fires involving ordinary combustibles like wood and paper rather than flammable liquids.

Understanding the specific types of foam and their applications is crucial for effective fire suppression in various scenarios, enhancing safety and effectiveness during firefighting operations.