Can a centrifugal pump be used to regulate flow by closing the outlet valve? Why?
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Can a centrifugal pump be used to regulate flow by closing the outlet valve? Why?
Yes, that’s a characteristic of centrifugal pumps. Flow rate, head, and power are correspondingly matched, achieving the highest efficiency at the design point.
Theoretically, it is not allowed to adjust the flow rate by closing the outlet valve, as this wastes the pump’s efficiency; however, in practice, outlet valves are used to regulate flow rate when larger pumps are selected.
Especially when a large motor is used to drive a small pump, the pump outlet valve is often used to regulate the flow rate when there is no control valve on the outlet pipeline.
Because centrifugal pumps do not allow flow regulation by adjusting the opening of the inlet valve……
Flow is blocked by controlling the cross-sectional area of the pump outlet valve, simply to achieve the desired effect.
If the flow rate cannot be adjusted through the outlet valve, then what methods are there to adjust it? Using variable frequency?
Yes, the efficiency of the pump can be reduced in order to change the flow rate
The pump should regulate the outlet pressure through the outlet valve; the head and flow rate on the pump’s performance curve are related to each other, so it can also be said that it is used to regulate the flow rate.
There are three schemes for controlling the outlet flow rate of centrifugal pumps: 1. Install a control valve on the outlet pipeline to directly throttle the flow； 2. Change the pump speed (using frequency conversion for electric motors, and steam flow rate for steam turbines) ； 3. If there is a bypass, install a control valve on the bypass pipeline to adjust the bypass flow rate.