Where is the most likely time for damage to occur if a centrifugal pump's check valve leaks?

• A. During shutdown
• B. On startup of the pump
• C. During continuous operation
• D. When the valve is closed

Answer: (B)

Starting a centrifugal pump is when the system undergoes the largest rapid change in pressure and flow. As the pump accelerates, the discharge pressure climbs quickly. If the check valve leaks, fluid can slip back through the valve as it tries to open, causing a momentary reverse flow and a sudden pressure spike in the line. That transient subjects the valve seat, seals, and piping to shock loads and possible damage. In steady operation the flow is stable, and during shutdown the valve is closed to prevent backflow, so the stresses are much less. So, the most likely time for damage to occur is during startup of the pump.