Issue with the shutdown head pressure of 2 pumps in series? If anyone skilled knows how, please come and give some advice
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Suppose there are 2 pumps connected in series: the first pump has a head of 200 m, while the pump connected after it has a head of 1000 m. Assuming the shutdown head coefficient is 1.3, should the head at the outlet of the pump connected behind be calculated as 1000 m × 1.3 = 1300 m, or should the head from the first pump also be taken into account, resulting in (200 m + 1000 m) × 1.3 = 1560 m? Are there any standards or documents that specify this? I forgot; I hope a friend who knows the way can give some advice. Thank you very much
This issue almost always arises; when selecting a pump, you should carefully study its Q-H curve in relation to the process requirements.
Of course, both the front and back aspects need to be considered; the 200 value mentioned earlier can be understood as the pump inlet pressure. Another bug: pumps with such high head pressure should not be turned off suddenly, as water hammer could easily damage the pipes
When considering shutting down the head, in order to determine the design pressure of the pipeline, is there any source that takes both the upstream and downstream conditions into account?
Regarding this issue, there are some matters that deserve attention and I hope they will be taken into consideration. Starting with the mechanical aspects, we need to determine what category this type of pump falls into – is it a centrifugal pump or a positive displacement pump? Then it is to check whether the operating conditions of the subsequent series pump meet the requirements of the pump. If it’s a positive displacement pump and the outlet valve is closed \"suddenly\", then if the system has enough capacity, there will be some time for buffering; otherwise, the safety valve will have to be used to release pressure. This approach seems risky, so it’s better to consider how to validate it and learn more about it.
When centrifugal pumps are connected in series, the flow rate remains the same; any changes occur simultaneously. Refer to the curves of 2-stage pumps to understand this behavior for multi-stage pumps as well
So you mean to calculate it using (200+1000) X 1.3, right? Thank you