A centrifugal pump containing two or more impellers is called a multistage centrifugal pump. The impellers may be mounted on the same shaft or on different shafts. For higher pressures at the outlet impellers can be connected in series.
For higher flow output impellers can be connected in parallel.
A common application of the multistage centrifugal pump is the boiler feedwater pump or to boost water pressure due to poor mains pressure.
All energy transferred to the fluid is derived from the mechanical energy driving the impeller.