# Centrifugal pump affinity laws

## CENTRIFUGAL PUMP AFFINITY LAWS 19-04

- The capacity or amount of fluid you are pumping will vary directly with this number.
- The head produced by the pump varies by the square of the number.
- The horsepower required changes by the cube of the number
- The net positive suction head required by the pump manufacturer (NPSHR) varies approximately by the square of the number.
- The amount of shaft run out (deflection) varies approximately by the square of the number
- The amount of friction loss in the piping varies approximately by 90% of the square of the number. Fittings and accessories vary approximately by the square of the number.
- The wear rate of the components varies approximately by the cube of the number.