A centrifugal pump can be started or stopped against what condition?

A centrifugal pump can be started or stopped against what condition?

• A. High head
• B. Low suction
• C. Open discharge valve
• D. Closed discharge valve

Answer: (D)

Starting or stopping a centrifugal pump with the discharge valve closed keeps the hydraulic load low during acceleration or deceleration. When the valve is closed, there’s almost no flow, so the pump isn’t fighting against system head. This minimizes inrush current and mechanical stress on the motor and impeller, and it avoids sudden pressure surges in the discharge piping (water hammer) that can occur if the valve is open or partially open during start or stop. If you tried to start against a high head or with the discharge valve open, the pump would have to overcome the full system head immediately, causing higher torque demand, potential stall or overheating, and greater risk of hydraulic shocks when you later open the valve. So the best practice is to start or stop against a closed discharge valve.

Starting or stopping a centrifugal pump with the discharge valve closed keeps the hydraulic load low during acceleration or deceleration. When the valve is closed, there’s almost no flow, so the pump isn’t fighting against system head. This minimizes inrush current and mechanical stress on the motor and impeller, and it avoids sudden pressure surges in the discharge piping (water hammer) that can occur if the valve is open or partially open during start or stop. If you tried to start against a high head or with the discharge valve open, the pump would have to overcome the full system head immediately, causing higher torque demand, potential stall or overheating, and greater risk of hydraulic shocks when you later open the valve. So the best practice is to start or stop against a closed discharge valve.