What type of pump is not seriously damaged if the discharge valve is closed for a short time while the pump is running?

What type of pump is not seriously damaged if the discharge valve is closed for a short time while the pump is running?

• A. Diaphragm pump
• B. Centrifugal pump
• C. Piston pump
• D. Plunger pump

Answer: (B)

When a discharge is closed while a pump is running, the situation depends on how the pump handles flow and pressure. A centrifugal pump responds to a blocked discharge by increasing the head up to its shut-off head, but it does not trap a fixed volume of liquid with each stroke. Because the liquid isn’t confined in a single, incompressible pouch, a brief dead-end condition causes a transient rise in pressure that the pump and piping can typically withstand for a short time without serious damage. In contrast, positive-displacement pumps (like piston, plunger, or diaphragm types) trap a fixed amount of liquid with every cycle. If the discharge is blocked, that trapped liquid is compressed against the closed valve, creating very high pressure spikes (and potential water hammer) that can quickly damage seals, valves, cylinders, and fittings—even with a short closure. So, a centrifugal pump is the type best able to tolerate a short discharge closure without serious damage.

When a discharge is closed while a pump is running, the situation depends on how the pump handles flow and pressure. A centrifugal pump responds to a blocked discharge by increasing the head up to its shut-off head, but it does not trap a fixed volume of liquid with each stroke. Because the liquid isn’t confined in a single, incompressible pouch, a brief dead-end condition causes a transient rise in pressure that the pump and piping can typically withstand for a short time without serious damage.

In contrast, positive-displacement pumps (like piston, plunger, or diaphragm types) trap a fixed amount of liquid with every cycle. If the discharge is blocked, that trapped liquid is compressed against the closed valve, creating very high pressure spikes (and potential water hammer) that can quickly damage seals, valves, cylinders, and fittings—even with a short closure.

So, a centrifugal pump is the type best able to tolerate a short discharge closure without serious damage.