Identify the type of foam concentrate storage tank that cannot be refilled during operation.

Identify the type of foam concentrate storage tank that cannot be refilled during operation.

• A. Piston tank
• B. Pressure proportion tank
• C. Gravity feed tank
• D. Double-wall tank

Answer: (B)

In foam concentrate storage, the ability to refill while the system is live depends on how the tank is pressurized and integrated with the proportioning loop. A pressure proportion tank is kept under pressure to push concentrate into the system; its fill is tied to the active loop, so opening it or attempting a refill during operation would disrupt the pressure, affect the foam mix, and potentially release foam or gas. Because of that, it must be refilled only after the system is shut down and the tank is depressurized. Other tank types rely on different mechanisms (a piston-driven displacement, gravity feed, or merely containment) and are not inherently restricted from refilling while the system is offline or isolated, which is why the pressure proportion tank is the one that cannot be refilled during operation.

In foam concentrate storage, the ability to refill while the system is live depends on how the tank is pressurized and integrated with the proportioning loop. A pressure proportion tank is kept under pressure to push concentrate into the system; its fill is tied to the active loop, so opening it or attempting a refill during operation would disrupt the pressure, affect the foam mix, and potentially release foam or gas. Because of that, it must be refilled only after the system is shut down and the tank is depressurized. Other tank types rely on different mechanisms (a piston-driven displacement, gravity feed, or merely containment) and are not inherently restricted from refilling while the system is offline or isolated, which is why the pressure proportion tank is the one that cannot be refilled during operation.