Which of the following is NOT a low-energy foam proportioning system?

• A. Compressed Air
• B. Balanced Pressure
• C. In-line Eductor
• D. Direct Injection

Answer: (A)

Low-energy foam proportioning uses the water flow and pump pressure itself to mix foam concentrate into the water stream. In-line eductors work by Venturi effect, drawing concentrate into the flow with no external energy source beyond the pump. Balanced-pressure proportioning maintains equal pressures so concentrate is drawn in as the water moves, again using the pump’s energy. Direct injection uses a controlled injector or metering pump to introduce concentrate into the discharge stream, relying on the system pressure rather than additional energy sources. Compressed air foam systems add an air compressor to mix air with the foam solution, creating expanded foam, which requires extra energy. That additional energy makes it not a low-energy system. So the method that is not a low-energy foam proportioning system is the compressed air system.