This implies a pump head-flow characteristic that falls continuously from shut valve to duty point by at least 10%.

Centrifugal pump characteristic curve on the efficiency of the highest point known as the design point, a pump at the point corresponding to pressure head and flow of work under the most economic.

There exists a saddle type zone in the hydraulic moment curve of axial-flow pump blades which corresponds to the saddle zone of discharge-head characteristic curve of the pump.