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Anonymous Poster

### Power of motor?

11/27/2007 1:10 AM

what should be the power of the motor required to drive a pump of capacity 7000m3/hr?

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Power-User

Join Date: Dec 2006
Location: Vietnam
Posts: 154
#1

### Re: Power of motor?

11/27/2007 2:27 AM

Please tell us, what the pressure of pump is?

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Guru

Join Date: Jan 2007
Location: Centurion, South Africa
Posts: 3776
#2

### Re: Power of motor?

11/27/2007 3:12 AM

You would first require the working pressure = Static head + working pressure at outlet + losses (friction + obstructions)

Then you would require the efficiency of the pump at the duty point

You then have to take drive losses into account

and the factor of the driver.

Supply as much of the above as available.

Do you have the pump already?

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Power-User

Join Date: Dec 2006
Location: Vietnam
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#3

### Re: Power of motor?

11/27/2007 3:28 AM

Best regard.

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Anonymous Poster
#4

### Re: Power of motor?

11/27/2007 4:36 AM

what should be the power of the motor required to drive a pump of capacity 7000m3/hr and the pressure difference is 5kg/cm2? The efficiency of the pump is 90%.

Power-User

Join Date: Jun 2005
Posts: 398
#6

### Re: Power of motor?

11/28/2007 2:02 PM

I have to convert to IP.

7000 stere/hr = 30,819 gpm

5 kg/cm2 = 71.0 psi = 164 ft

pump efficiency = 90% (given)

bhp = (gpm * tdh * G)/(3960 * eff.) = 1,418

G = specific weight of water = 1

This assumes that the pressure difference is total dynamic head, which is just the differential pressure across the pump if the diameter of the pipe upstream and downstream is the same as is the elevation.

To get power required, divide the brake horse power by motor efficiency (probably around 96%) and multiply by .7457 to get kilowatts.

Guru

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#5

### Re: Power of motor?

11/27/2007 4:47 AM

Shaft power for any fluid mover = pressure rise x volumetric flowrate (in compatible units).

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