Multistage centrifugal pumps

The flow is thus directed from the outlet of the preceding impeller into the inlet of the following one. The high-pressure centrifugal pump is often designed as a ring-section pump.

With the same design, the delivery pressure (delivery head) increases proportionally to the number of impellers for the same flow rate. If the additional losses due to flow diversion in the inlet and outlet are neglected, the hydraulic efficiency is independent of the number of stages. Thus the characteristic curves of multistage centrifugal pumps can be converted as follows as a good approximation:

H_n(Q) = n/m · H_m(Q)
P_2,n(Q) = n/m · P_2,m(Q)
η_hydr,n(Q) = η_hydr,m(Q)
NPSH_n(Q) = NPSH_m(Q)

n, m - Number of impellers
Q - Flow
H - Head
P2 - Shaft power
η - efficiency