Check valves are used on the discharge side of centrifugal pumps to

• A. Equalize the pressure on both sides of the impeller
• B. Prevent water in the suction line from flowing back into the reservoir
• C. Regulate the rate of water flow through the discharge pipe
• D. Prevent water in discharge line from flowing back

Answer: (D)

Preventing backflow in the discharge line is the purpose of a check valve on a centrifugal pump. When the pump is running, the valve remains open to allow one-way flow from the pump into the system. If the pump stops or downstream pressure drops, the check valve closes to stop water from flowing backward toward the pump or back toward the source, which helps maintain system pressure, protect the pump, and prevent loss of prime. It doesn’t serve to equalize pressure across the impeller or regulate flow rate, and backflow in the suction line is handled by a valve on the suction side, not the discharge side.