Minimum outlet pressure of centrifugal pump
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Is there a minimum value for the outlet pressure of a centrifugal pump? For example, must the outlet pressure of a centrifugal pump with a head of 50 meters remain above 5 kilograms? What impact does it have on a centrifugal pump if its outlet pipeline is too large or the valve is opened too wide, resulting in very low outlet pressure?
This post was last edited by ylb913 on 2015-7-12 22:25. There is no flow display at the pump outlet; it would be ideal to have one, but if not, current measurement can be used. While measuring the current, adjust the opening degree of the outlet valve to find an appropriate outlet pressure control value.
The outlet pressure of a centrifugal pump is related to its inlet pressure. Under the same conditions, the lowest pressure occurs when the outlet valve is fully open; at this point the pressure is minimal, but the flow rate is highest, and the current consumption is also high.
There is generally no minimum value for the outlet pressure of centrifugal pumps, as the curve shapes of different pumps vary and the densities of the fluids they transport differ, which makes it impossible to determine an exact minimum value. However, the discharge pressure should not be too low; if it is too low, it indicates that the pump’s flow rate is set too high, which can lead to issues such as excessive current, increased pump vibration, cavitation, and unstable pump operation.
When the flow rate is high and the pressure is low, on the one hand, the shaft power increases and the current rises, which may lead to overcurrent. On the other hand, the cavitation curve of a pump generally rises as the flow rate increases, so pumps often experience vibration and cavitation.
This depends on the performance curve of the pump; as the flow rate changes, so do the head, efficiency, power, and net positive suction head
The level of pressure is merely a superficial indicator; what’s most important is that it reflects the performance of the motor. By examining the pressure value, it is possible to determine whether the pump is operating properly. Too low pressure indicates excessive flow; it’s not a big problem as long as the motor isn’t experiencing overcurrent ； Excessive pressure is dangerous; it may even damage the mechanical seal or the pump itself.
Each pump has its own flow-pressure characteristic curve; the minimum pressure within the allowable range can be determined from this curve, although this value is generally not specified.