While using centrifugal pumps, if a _____ head is to be developed, the impellers are connected in _____.

Explanation:

If a centrifugal pump consists of two or more impellers, the pump is called a multistage centrifugal pump. The impeller may be mounted on the same shaft or on different shafts.

A multistage pump is having the following functions:

To produce high heads:

For developing a high head, a number of impellers are mounted in series or on the same shaft.

N = Number of identical impellers mounted on the same shaft

Hm = Head developed by each impeller

Total head developed = N × Hm

The discharge passing through each impeller is the same.

To discharge a large quantity of liquid:

For obtaining a high discharge, the pumps should be connected in parallel.

N = Number of identical pumps arranged in parallel

Q = Discharge from one pump

Total discharge = N × Q

Each of the pumps is working against the same head.