Quick way to determine pump Head and Capacity by increase impeller diameter

Here I would like to share with you all the quick way to determine pump Head and Capacity by increase impeller diameter.

Normally centrifugal pump will have 10~20 % allowance if the impeller size increase to max.

For example : original impeller diameter D1 = 301mm  D2 = 320mm and pump head  H1 = 33

The new pump head H2 will be (D2/D1)^2 * H1

and for the pump capacity, as well you can do calculate in this formulae

Quick way to determine Q2 will be (H2/H1)*Q1