Affinity Laws for Pumps and Hydraulic Machinery

One of the pump characteristics is that its load torque is proportional to the square of its revolving speed, and this torque is called square reduction torque load.

Relationship between speed of revolution N (rpm) and flow rate Q (m3/sec.)
Flow rate is proportional to the speed of revolution. QαN

Relationship between speed of revolution N (rpm) and head H (m)
Head is proportional to the square of speed of revolution. HαN2

Relationship between speed of revolution N (rpm) and power P (kW)
Power is proportional to the cube of speed of revolution. PαN3

Relationship between speed of revolution N (rpm) and torque T (N-m)
Torque is proportional to the square of speed of revolution. TαN2