Ohio Volunteer Firefighter Practice Exam

What is filled in foam fire extinguishers?

1. Water solution

2. Compressed air

3. Pretreated water

4. Premixed foam solution

The correct answer is: Premixed foam solution

Foam fire extinguishers are specifically designed to combat fires involving flammable liquids, such as gasoline or oil. The correct answer indicates that foam fire extinguishers are filled with a premixed foam solution. This foam is created by mixing water with a foam concentrate, which produces a stable and thick foam when expelled from the extinguisher. This foam acts as a barrier between the fuel and the oxygen in the environment, effectively smothering the fire and cooling the burning surface. The premixed nature of the foam solution ensures that it can be readily deployed and will function effectively to suppress flames. Other options, such as a water solution or compressed air, do not provide the necessary extinguishing properties required to effectively combat flammable liquid fires. Water can spread such fires due to the oil or fuel component, while compressed air alone would not have the properties needed to suppress or eliminate the fire. Pretreated water also lacks the foam-forming ability needed to suffocate the fire effectively. Thus, the premixed foam solution is the only option that aligns with the specific purpose and function of foam fire extinguishers.