Centrifugal Pumps in Series

The Centrifugal pumps are employed in series to overcome a larger system head loss than one pump can reimburse for separately. As shown in figure below, the two similar centrifugal pumps operating at the similar speed with same volumetric flow rate contribute the similar pump head. As the inlet to the second pump is the outlet of the first pump, the head generated by both pumps is the total of the separate heads. The volumetric flow rate from the inlet of the primary pump to the outlet of the second stays the same.

Figure: Pump characteristic curve for two identical Centrifugal pumps used in sequence

As shown in figure below, by using two pumps in sequence does not really double the resistance to flow in the system. The two pumps give sufficient pump head for the new system and also sustain a little higher volumetric flow rate.

Figure: Operating point for two Centrifugal pumps in series