Error 1
If a centrifugal pump is operated with the discharge valve closed (shut-off), the pump develops maximum pressure.
Answer
Centrifugal pumps develop maximum pressure at shut off only if the pump has a stable curve. Stable curve pumps exhibit a relatively continuous, steady, and smooth rate of pressure drop as flow increases from shut-off all the way out to maximum flow. However not all pumps have stable curves.
There are many commercially available unstable curve pumps. The majority of those unstable curve pumps exhibit the instability at low flow down to shut off, and those pumps are said to have "droop". The most common form of droop is where pressure is highest at about 10% of BEP, with pressure dropping slightly from that 10% point down to shut-off.
Select the links below to see examples and explanations of stable and unstable pump curves.
