How many types of low-energy foam proportioning systems are installed on ARFF apparatus?

• A. One
• B. Two
• C. Three
• D. Four

Answer: (B)

Low-energy foam proportioning relies on the hydraulic energy of the water flow to mix foam concentrate, rather than using a high-energy foam pump. On ARFF apparatus, this approach has two common implementations. One is a venturi/eductor style integrated into the discharge line: as water moves through, it creates suction that pulls foam concentrate from a reservoir into the stream, producing a foam solution at a set ratio. The other uses a small metering pump that injects a precise amount of foam concentrate into the water line, giving controlled proportions across a range of flow rates. Both methods achieve foam solution without relying on high-energy systems, which is why they’re classified together as low-energy approaches. Different ARFF models may use either arrangement, which is why the standard answer is two.