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# Orifice On Pump Discharge Line

5 replies to this topic
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### #1 Ranga v

Ranga v

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Posted 01 November 2018 - 10:52 AM

I have a higher capacity  pump of 47m3/hr and head 81 m ,My Processs requirement is 25 m3/hr and 6 kg/cm2.

I want to use the same pump by providing a orifice at discharge line.

Process fluid is water ,suction pressure is 3.5 kg/cm2,temp-ambient.I wan the orifice dia calculation for the process stream.

### #2 fallah

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Posted 01 November 2018 - 11:04 AM

I have a higher capacity  pump of 47m3/hr and head 81 m ,My Processs requirement is 25 m3/hr and 6 kg/cm2.

I want to use the same pump by providing a orifice at discharge line.

Process fluid is water ,suction pressure is 3.5 kg/cm2,temp-ambient.I wan the orifice dia calculation for the process stream.

Ranga,

Go to find the corresponding head of 25 m3/hr flow rate on the pump curve. Then convert it to gauge pressure, say P1, as new pump discharge pressure or upstream pressure of the restriction orifice.

Now, the orifice should be sized based on DeltaP=P1-6 kg/cm2 and passing water flow rate of 25 m3/hr to be installed along the discharge line with specified diameter.

### #3 Bobby Strain

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Posted 01 November 2018 - 02:27 PM

Maybe you don't need an orifice.

Bobby

### #4 breizh

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Posted 02 November 2018 - 03:58 AM

Hi ,

What about machining the impeller  or use a VSD ?

Check the pump curve first as pointed out by Bobby .

Breizh

Edited by breizh, 02 November 2018 - 04:35 AM.

### #5 shan

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Posted 02 November 2018 - 06:04 AM

It seems you are talking about a centrifugal pump.

A fixed opening orifice may just fit your specified design case flow and pressure but it is unable to meet all the off design case flows and pressures.  You may consider a recycle loop to satisfy all your operation scenarios.

### #6 spiderbat11

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Posted 12 November 2018 - 10:51 AM

If you are talking about centrifugal pumps its always better to go for impeller trimming based on the OEM pump curve. Installation of VFDs will gain add to overhead cost and maintenance cost