What characterizes low expansion foam?

Low expansion foam is characterized by its ability to produce a dense, stable foam that contains relatively little air and generates small bubbles. This type of foam is designed to create a thick blanket over a fire, effectively suppressing it by forming a barrier that prevents oxygen from reaching the flames. The small bubbles of low expansion foam contribute to its effectiveness in sealing off the fuel surface and minimizing flammable vapors, which is essential in extinguishing class B fires, particularly those involving flammable liquids.

The nature of the foam produced is crucial in firefighting applications, as the density and stability of the foam can significantly impact its performance in controlling fires. Low expansion foam is particularly useful for creating longer-lasting coverage on the surface of the burning material, which conventional air-filled foams may not achieve.

In comparison, other options do not capture the defining characteristics of low expansion foam. High expansion foams, for instance, would produce large bubbles with considerable air mixes, while the references to protein content and alcohol-resistant properties align more closely with different types of foam designed for specific firefighting challenges.