Pump Characteristic Curve
Unlike centrifugal pump, Rotary pump do not generate pressure. Instead it works against the back pressure of a given system. The characteristic of the curve is very dependent on the liquid properties especially the viscosity of the liquid. The speed of the pump at a given viscosity will also play a role in the forming the pump curve.
Positive Displacement Pump Curve
Figure 10. A positive displacement pump performance curve
Figure 10 illustrates the characteristic curve for a rotary type positive displacement pump.