Calculation and design of the inlet main pipe for two operating pumps and one standby pump
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Hello, experts. May I ask how to calculate the diameter of the pipeline at the pump inlet manifold for a system with two operating pumps and one standby pump? Also, how can we avoid water competition issues? Thank you, https://attach01.hcbbs.com/forum/201905/11/100821v3tjsq9y0t3ptn72.png
Although the inlet valves should be fully open, I have indeed seen situations where, as you mentioned, the inlet valves of each pump are adjusted to be slightly closed, resulting in different degrees of opening for these valves. This is done in order to regulate the inlet pressure of multiple pumps; the inlet pressure serves as the reference point (with a pressure gauge installed at the pump inlet), so that all pumps operate under the same conditions. (This also involves coordinating the inlet and outlet valves.) However, such an approach can only be used when the net positive suction head available in the system is much greater than that required by the pumps, and it is applicable when there is a long straight section of pipe leading up to the inlet. Therefore, in such cases, the diameter of the main pipe needs to be large enough; otherwise, the inlet valve cannot be adjusted properly.
This is a less common approach; to properly control the flow rate of the pump, it is still necessary to use a flow meter along with an outlet valve for control