In a foam concentrate tank, what component separates concentrate from water?

• A. Internal bladder
• B. External bladder
• C. Gravity feed
• D. No separation

Answer: (A)

Foam solution tanks use a flexible barrier to keep the concentrate separate from the water until it’s time to mix. An internal bladder sits inside the tank and holds the concentrate. When the system is pressurized, water pushes against the bladder, forcing the concentrate out through the discharge line into the foam proportioning path. Because the concentrate is contained in the bladder, it doesn’t mix with the water during storage, which preserves the correct concentrate-to-water ratio and prevents contamination of the water supply. External bladders work on the same principle but are located outside the main tank. Gravity feed describes how liquid moves rather than how the separation is achieved, and no separation would allow premature mixing and loss of control over the foam solution.