Which foam type is effective at suppressing hydrocarbon fires?

Aqueous Film Forming Foam (AFFF) is specifically designed to suppress hydrocarbon fires effectively. It works by forming a film that smothers the fire and prevents vapors from escaping, which is crucial for hydrocarbon fires where the fuel can be readily ignited. AFFF contains fluorinated surfactants that help create this protective film over the burning liquid, enabling it to rapidly extinguish the flames.

Class B foam is another correct choice in a broader context, as it encompasses various types of foams suitable for flammable liquid fires. However, AFFF is particularly recognized for its rapid application and strong effectiveness on hydrocarbon fuels.

Protein foam works effectively for hydrocarbon fires but is generally slower and less effective than AFFF in quick extinguishment scenarios. Similarly, dry chemical foam is great for suppressing fires but can be less effective against hydrocarbon fires compared to AFFF.

Thus, while other options may have some effectiveness, AFFF stands out for its specialized purpose and rapid action in suppressing hydrocarbon fires.