Eduction, or induction, uses which principle to draw foam concentrate into water?

• A. Centrifugal mixing
• B. Hydraulic injection
• C. Magnetic coupling
• D. Venturi method

Answer: (D)

Eduction draws foam concentrate into water by the Venturi effect. As water is forced through a narrow throat in the eductor, its velocity increases and its pressure drops. The lower pressure creates suction that draws foam concentrate up from its reservoir into the water stream, mixing to form the foam solution. This relies on Bernoulli’s principle—the faster the water flows through the constriction, the lower the pressure, which entrains the concentrate without needing a separate pump. Other methods would use different mechanisms, but the Venturi-induced suction is what makes eduction possible.