Pumps in Series and Parallel

series: H = \sum H_{i} (Q same) parallel: Q = \sum Q_{i} (H same)

Identical pumps in series add heads at a given Q (good for high head). In parallel they add discharges at a given H (good for high flow). The combined curve is matched to the system curve H = H_static + K Q² to find the operating point.

$H$ (m): Head
$Q$ (m³/s): Discharge

Step-by-step solved example

One pump: 30 m at 0.04 m³/s. Two identical pumps in series at that Q? In parallel at that H?

Series: heads add at the same Q. Parallel: discharges add at the same H.

1. Series
Same Q = 0.04 m³/s, H = 30+30 = 60 m.
2. Parallel
Same H = 30 m, Q = 0.04+0.04 = 0.08 m³/s.

Answer: Series: 60 m @ 0.04 m³/s; parallel: 0.08 m³/s @ 30 m

10 practice questions

0/10 correct

1.Series pumps (identical) at a given Q

2.Parallel pumps at a given H

3.A steep system curve (high friction) often favors

4.Operating point is the intersection of

5.Shutoff head is

6.Runout / free delivery is

7.Two unlike pumps in parallel share

8.Affinity: Q2/Q1 = N2/N1 and H2/H1 =

9.Power scales with speed roughly as

10.A check valve on a parallel pump prevents