Which describes the process to get foam into the line?

• A. Injected into the nozzle
• B. Mixed at the hydrant
• C. Inducted into the line
• D. Added at the pump

Answer: (C)

Introducing foam into the water stream is done by induction through a foam proportioning device. The foam concentrate is drawn from its container and pulled into the flowing water by an eductor or inductor installed in the discharge line. This method uses the Venturi effect to mix the concentrate with the water as it moves toward the nozzle, ensuring the correct foam solution is created and uniform mixing throughout the line. It places the foam into the system ahead of the nozzle so the mixture is consistent as it travels through the hose.

Injected into the nozzle would place concentrate at the tip and can lead to uneven mixing or nozzle clogging. Mixing at the hydrant isn’t standard practice because proper proportioning and mixing typically happen in the pump discharge line, not at the hydrant itself. Adding at the pump can work in some setups, but induction through a dedicated proportioner is the controlled, reliable method used to achieve the correct foam-to-water ratio.