When two identical centrifugal pumps are operated in parallel in an irrigation pipeline system, the combined pump characteristic curve is obtained by:
Options:
(A) Adding their discharges ($Q = Q_1 + Q_2$) at identical heads
(B) Adding their heads ($H = H_1 + H_2$) at identical discharges
(C) Multiplying their respective heads and dividing by discharge
(D) Taking the geometric mean of their head curves
Answer Key:
A
Step-by-Step Solution & Explanation
- Parallel pump operation: Both pumps discharge into a common delivery manifold against the same total head. Therefore, the combined characteristic curve is obtained by adding the discharges of each pump at each head ($Q_{\text{total}} = Q_1 + Q_2$ at constant $H$).
- Series pump operation: The discharge flows sequentially through both pumps, so heads add up ($H_{\text{total}} = H_1 + H_2$ at constant $Q$). Option A is correct.