Easy Way to Understand the Pump Performance Curve

We need to understand the operating condition in the consideration for pump selecting in previously introduced. After understanding the basic concepts, it is necessary to explain how to read the "pump performance curve (H-Q curve)". The performance of each pump model is different, and the most suitable pump must be selected according to the pump performance specifications and the operating conditions provided by the customer.

 

In the performance curve diagram, the horizontal axis is the CAPACITY (Q), the left side of the vertical axis is the HEAD (H), and the right side of the vertical axis is the EFFICIENCY (%) and shaft power.

The first gray straight dotted line is the shaft power curve under the maximum diameter of the impeller, the second gray straight dotted line is the shaft power curve under the minimum diameter of the impeller, and the red straight line(POWER) is the pump shaft power performance curve that meets the operating requirements provided by the customer.

 

The first gray dotted curve in the figure is the performance curve under the maximum diameter of the impeller, the second gray dotted curve is the performance curve under the minimum diameter of the impeller, and the red curve(TDH) is the performance curve that meets the customer's operating requirements of the pump, we call duty point, which is what we get by adjusting the size of the impeller, showing the relationship between capacity and head. The green curve(EFF) is the operating efficiency of the pump.

 

 

According to the flow demand of the horizontal axis, you can find the duty point by comparing the red curve upwards. By comparing the duty point to the left and right vertical axis, we can know the head and efficiency; then comparing the red line upwards, from the intersection (shaft power) to the right vertical axis, we can know how much the power is under this operating condition.

 

The efficiency of the pump depends on the duty point, and the change of the duty point will also have a great impact on the field process, so the correct selection of the pump is very important.

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