Allied & ICAR Exam Bank • ALLIED_1248NAT • 2 Marks
Section 5: Irrigation and Drainage Engineering
Centrifugal Pumps and Cavitation
Subtopic: Pump Power Requirement
Question Statement:
An irrigation pump discharges $40\text{ L/s}$ ($0.040\text{ m}^3/\text{s}$) against a total dynamic head of $25\text{ m}$. If the pump efficiency is $70\%$, the required pump shaft input power in kW is: (Take $g = 9.81\text{ m/s}^2$ and $\rho = 1000\text{ kg/m}^3$)
Answer Key:
14.0
Step-by-Step Solution & Explanation
Water horsepower $P_{water} = \rho g Q H = 1000 \times 9.81 \times 0.040 \times 25 = 9810\text{ W} = 9.81\text{ kW}$. Shaft power $= \frac{9.81}{0.70} \approx 14.01\text{ kW}$.