Florida Fire State Practice Exam

Which proportioning method depends on the venturi principle to draw foam through a hose?

1. Batch mixing

2. Direct injection

3. Eduction

4. Self-eduction

The correct answer is: Eduction

The method that relies on the venturi principle for drawing foam through a hose is eduction. This principle works by utilizing the change in pressure that occurs when a fluid flows through a constricted section of piping, which creates a vacuum that draws in the foam concentrate and mixes it with water. In the context of fire suppression, eduction systems incorporate a device called an eductor, where water flows through a venturi-shaped tube, causing a reduction in pressure that pulls foam concentrate from a container. This allows for consistent mixing and application of foam at the correct proportions directly into the firefighting line, enhancing the effectiveness of the foam in suppressing fires. The other methods, such as batch mixing, involve preparing a mixture of foam concentrate and water in a separate container before application, and direct injection involves injecting foam directly into the water stream without relying on the venturi effect. Self-eduction refers to a system that may not require an eductor and can be less efficient in utilizing the venturi principle. Therefore, eduction is the most accurate answer as it specifically describes the method that employs the venturi principle for foam application.