The performance parameters of the pump main flow and head, in addition to the shaft power, speed and essential NPSH. Flow is refers to the unit time through the pump export amount of liquid output, generally USES the volume flow; Head is the unit weight transport the liquid from the pump inlet to export energy increment, for positive displacement pump, energy increment mainly reflects in pressure can increase, so often in the pressure head to say instead of increment.
  The pump efficiency is not an independent performance parameters, it can be made by other performance parameters such as capacity and head and shaft power obtained according to the formula to calculate. Conversely, the known capacity and head and efficiency, also can seek the shaft power. Each performance parameters of the pump exist between certain mutually dependent relationship can through to the pump to test, measure and calculate respectively parameter value, and painted curve to says, the curve is called the performance curves of pump. Every pump have certain characteristic curve, by the pump manufacturer provides. Usually in the factory the characteristic curve are also marked the performance of the recommended section, called the pump working range.