Regarding the issue of valve opening degree with a variable-frequency pump
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Do pump valves with variable frequency need to be set to full capacity? Will the efficiency decrease? Why?
No, as long as you control the rotation speed, there will be no problem
Variable frequency is used to adjust the load on the pump; if the valve must be fully open in order to achieve the system’s maximum load, then the valve needs to be kept fully open.
Variable frequency control and valve control are two methods for adjusting pump flow; variable frequency control is primarily aimed at saving energy, whereas valve control does not help with energy savings. If frequency conversion control is used while the valve is not fully open (increasing the resistance in the pipeline), this method offers little energy savings; in fact, it consumes more energy than controlling the valve alone.
The pump outlet valve is fully open; flow can be controlled solely by adjusting the frequency