Civil Engineering - Water Supply Engineering - Discussion

20. 

To pump water from a water reservoir 3 m deep and maximum water level at 135 m, a pump is installed to lift water up to R.L. 175 m at a constant rate of 36, 00, 000 litres per hour. If the length of the pipe is 1506 m and f = 0.01, ignoring other minor losses and assuming the economical diameter from Lea's formula D = 1.2 Q, the water horse power of the pump is

[A]. 400
[B]. 450
[C]. 500
[D]. 580
[E]. 600

Answer: Option E

Explanation:

No answer description available for this question.

Mayank said: (Nov 30, 2016)  
The answer is 580.

Sujoy Basak said: (Jun 24, 2017)  
Give the workout of this problem.

Dhanu said: (Sep 17, 2017)  
Discharge = 1 m3/sec (converted),
dia = 1.2 root (1) = 1.2 m,
Q = area * velocity.
velocity = 0.884 m/s.

Lift of pump = R.L of high level - R.L of low level + depth of sump well
175-135+3 = 43m,
Frictional loss of head in the rising main = 4flv^2/2gd.
4*0.01*1506*0.884^2 / (2*9.81*1.2) = 1.999m,
assume loss in bends = 0.3m,
TOTAL HEAD = 43+0.3+1.999 = 45.30 m.

H.P of pump = WQH/75.
1000*1*45.30/75 = 604 = 600 given.

Pawan said: (Mar 19, 2019)  
Thanks @Dhanu.

Pawan said: (May 24, 2019)  
Thanks @Dhanu.

Srv said: (Jun 20, 2019)  
Thanks @Dhanu.

Hariom Chaurasia said: (Jul 22, 2019)  
Thanks for explaining @Dhanu.

Deepti said: (Dec 4, 2019)  
Nice explanation thank you.

Nomore said: (Apr 11, 2021)  
@Dhanu.

How did you come up with the value of 75 on H.P of pump= WQH/75?

Endale Abebe said: (Sep 23, 2021)  
Please explain the formula P=WQH/75.

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