Self-priming pump
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I have a self-priming pump that’s not in use and I want to use it, but I’ve noticed that its flow rate is too high. How low can the outlet valve be closed without damaging the pump? The pump’s head is 60 meters and its flow rate is 15 cubic meters per hour
The pump has a minimum flow rate; as long as the flow is above that minimum, it’s fine. However, a return pipe can be installed on the outlet pipeline
Whether it can be used depends on the extent of the traffic deviation; if the deviation is too large, no matter what approach is taken, it will be like using a heavy vehicle for a minor task, resulting in uneconomic operating costs； I was wondering if considering adding another frequency converter might be an option ； Change the traffic ； (But the frequency of changes cannot be too low, otherwise the motor may burn out due to poor heat dissipation.)
We normally take 1/3 of the design value for our minimum flow rate. . But sometimes 25% is also taken. .
It’s okay to reduce the flow rate of the water inlet valve using a water pump; however, reducing the flow rate of the outlet valve may cause problems for the pump. It is recommended to adopt the method used on the 2nd floor: add a return pipe from the outlet to the inlet, equip this return pipe with a valve, and adjust the flow rate of the return fluid in order to control the flow rate of the water exiting the system.
Reducing the outlet valve opening will inevitably cause the pump to heat up; this heating can lead to phenomena such as cavitation, which in turn results in abnormal pump operation or vacuum formation. It is not recommended to reduce the outlet valve opening; instead, a return flow can be used to meet the operational requirements.
Could we consider adjusting by closing both the inlet valve and the outlet valve at the same time? We have done this before
Just use a loop for the output. A bypass valve should be installed at the pump outlet (after the service valve and before the flow meter), using this bypass valve to control the flow rate
If it is a water pump, adding a return pipe along with a pressure control valve should suffice. For slurry pumps or those with a high solid content, it is recommended to use an inverter as suggested on the third floor for variable frequency control