What Is a Pump Characteristic Curve?

  Curves that express the relationships between the main performance parameters of a centrifugal pump are generally referred to as pump performance curves or characteristic curves. In essence, these curves are the external representation of the motion law of liquid inside the pump, and they are obtained through actual measurement.

Characteristic curves include the following four types:

Flow-head curve (Q-H)

Flow-efficiency curve (Q-η)

Flow-power curve (Q-N)

Flow-net positive suction head required curve (Q-(NPSH)r)

The function of characteristic curves is that for any given flow rate of the pump, a corresponding set of values (head, power, efficiency, and net positive suction head required) can be found on the curves. This set of parameters is called the operating condition, or operating point for short.

The operating condition corresponding to the pump’s maximum efficiency is called the optimum operating point, which generally coincides with the design operating point. In most cases, the rated parameters of a centrifugal pump are identical or very close to those of the optimum operating point.

In practical applications, operating the pump within the high-efficiency range not only saves energy but also ensures its normal operation. Therefore, it is quite important to understand the performance parameters of the pump.