What is the main purpose of a foot valve at the intake end of a suction line of a pump?

• A. Increase flow rate
• B. Maintain pump prime
• C. Prevent backflow
• D. Reduce pressure loss

Answer: (B)

The main purpose of a foot valve at the intake end of a suction line of a pump is to maintain pump prime. A foot valve is a type of check valve that is installed at the bottom of a suction line, submerged in the fluid. Its primary function is to ensure that the pump remains filled with liquid when it is turned off.

When the pump is operating, the foot valve opens, allowing the liquid to flow into the suction line. When the pump is turned off, the foot valve closes, which prevents the liquid from draining back out of the suction line and into the source. This is crucial because if the pump loses its prime (the liquid within its casing), it can lead to cavitation, reduced efficiency, or even damage to the pump itself upon restarting.

This mechanism is essential for the reliability and effective operation of pumps, particularly in applications where maintaining continuous operation is important. While aspects like preventing backflow and potentially influencing flow rate and pressure loss are associated with the operation of pumps, the specific and critical role of the foot valve is primarily focused on maintaining the pump's prime.