Can dynamic displacement pumps be started with the discharge valve closed or throttled?

Dynamic displacement pumps, including centrifugal pumps, are designed to handle flow and pressure changes due to their operational mechanics. When a dynamic pump is started with the discharge valve closed or throttled, the pump can still initiate operation because of the nature of how these pumps generate flow.

When the discharge valve is closed, the pump can create pressure because it spins and imparts energy to the fluid. This pressure build-up can happen until it reaches a specific level, often called the shut-off head. However, it is crucial to understand that while this starting condition is possible, it may not be advisable to keep the pump running under such conditions for extended periods. Running a pump against a closed discharge can lead to overheating or damage without the fluid flowing to carry away the heat generated.

Starting a pump with the discharge valve closed is permissible, but operational practices often recommend avoiding this scenario unless the pump is designed for such conditions or there are specific safeguards in place.