Florida Fire State Practice Exam

Class B foam is used to extinguish flames as well as to do what else?

1. Suppress vapors

2. Enhance fires

3. Cool down surfaces

4. Speed up combustion

The correct answer is: Suppress vapors

Class B foam is primarily designed to extinguish flammable liquid fires, such as those involving fuels, oils, and solvents. In addition to its extinguishing properties, Class B foam serves an important secondary function: it helps suppress vapors. This is crucial in preventing the re-ignition of flames that can occur when flammable vapors linger in the air after a fire has been extinguished. By creating a barrier over the surface of the burning liquid, the foam not only suffocates the flames but also limits the release of flammable vapors into the atmosphere, providing a more comprehensive approach to fire suppression. The other options do not accurately represent the role of Class B foam. Enhancing fires and speeding up combustion contradict the very purpose of fire suppression. Cooling down surfaces, while a useful action in firefighting, is not the primary function of Class B foam compared to vapor suppression.