Class B foam is used for which type of fires?

• A. electrical fires
• B. flammable and combustible liquids
• C. wood fires
• D. gas fires

Answer: (B)

Foam types are matched to the fuel involved in a fire. Class B foam is designed for fires involving flammable and combustible liquids, such as gasoline, diesel, oils, and solvents. It creates a stable foam blanket on the liquid surface, cooling the fuel and, importantly, separating the fuel from the air to reduce vapor release. This combination helps suppress the flame and prevents reignition. It isn’t the right choice for energized electrical fires, which require nonconductive agents; for solid combustibles like wood (Class A) the approach differs, and for gas fires the priority is usually shutting off the fuel source and applying other tactics rather than relying on foam. So, for fires involving flammable and combustible liquids, foam designed for Class B is the best option.