Here are some interesting web addresses that may be helpful.
How to Read a Pump Curve
A pump curve is a graphical representation of the performance of a pump based on the tests of the pump manufacturer. Every pump has its own curve and it varies very widely from pump to pump. The variation depends on many factors such as the kind of pump (centrifugal pump, turbine pump, vane pump etc.), its size and the shape of the impeller. Pump curves provide information on pump performance and absorbed power which is useful in determining the working point, the motor power and size.

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