What is the primary purpose of a foot valve when used with a centrifugal pump?

The primary purpose of a foot valve when used with a centrifugal pump is to keep the pump primed. A foot valve is a type of check valve that is installed at the bottom end of a suction pipe, submerged in the fluid. Its primary role is to prevent the backflow of water from the pump's suction line when the pump is not operating. By maintaining water in the suction line, the foot valve helps ensure that the pump remains full of fluid, allowing it to function efficiently when it is started.

This is crucial for centrifugal pumps, as they rely on being primed (filled with liquid) to operate effectively. If the pump loses its prime due to backflow, it may experience cavitation or fail to pump at all. In contrast, options related to regulating water flow, increasing pressure, or filtering impurities do not directly address the function of maintaining the pump's prime, which is essential for the proper operation of a centrifugal pump.