Check valves are used in connection with centrifugal pumps in order 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. Prevent water in the discharge line from flowing back.
• D. Regulate the rate of water flow through the discharge pipe.

Answer: (C)

Check valves in centrifugal pump systems are one-way devices that stop reverse flow. Placing a check valve on the discharge line prevents water being pushed toward the downstream piping from flowing back toward the pump when the pump stops or when discharge pressure drops. This helps keep the pump primed, protects downstream piping from reverse flow and potential water hammer, and maintains the intended flow direction. That’s why the correct choice is to prevent water in the discharge line from flowing back. A valve on the suction line could also prevent backflow into the reservoir, but the primary purpose described here is to stop backflow in the discharge path. Check valves do not regulate flow rate or directly equalize pressure across the impeller.