Pump performance curves

Performance curves for centrifugal pumps are different from curves drawn for positive displacement pumps. This is because the centrifugal is a dynamic device; that is, the performance of the pump responds to forces of acceleration and velocity. Note that every specific performance curve is based on a particular speed, a specific impeller diameter, impeller width, and fluid viscosity (usually taken as the viscosity of water).

Source: Handbook of water and wastewater treatment plant operations