Regarding some issues with pumps...
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I don’t have much work experience, and it’s in the field of processes. I would like to ask a few questions to those who are experts in equipment. First, can a multi-stage centrifugal pump be tested without any load? What causes heating at the high-pressure end? Regarding plunger pumps, why do some of them require the inlet and outlet valves to be opened before the pump can start? Why is the starting procedure for some of these pumps similar to that of centrifugal pumps? I hope experts will kindly provide some guidance: handshake
Neither multi-stage pumps nor single-stage pumps should be run without load. Primarily, when there is no fluid inside the pump, the lack of initial lubrication can lead to wear of the ring seals within the pump. This, in turn, causes dry friction in the mechanical seal, resulting in its failure. Especially in high-pressure pumps, where the balance drums and balance sleeves are often made of stainless steel, they tend to stick together; therefore, it is essential to avoid running multi-stage pumps without any fluid ； Plunger pumps belong to the category of positive displacement pumps; it is necessary to open the inlet and outlet valves in order to start the pump. Failing to do so can lead to problems such as pressure buildup at the outlet, which may trigger the safety valve to activate. In severe cases, this can cause mechanical damage. Centrifugal pumps are started with the outlet valve closed in order to reduce the starting current of the motor, but they cannot operate for long periods with the outlet valve closed. Generally, the outlet valve needs to be opened after 2–3 minutes; otherwise, the pump will overheat and become vacuumed.