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Centrifugal Pump Minimum Flow Requirement


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#1 ccwlun

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Posted 29 April 2019 - 08:24 PM

Dear Professional,

 

Regarding to the subject, I would like to ask if there is any standards specify the needs of provision the minimum flow line located before the check valve at the discharge line? The reason being during start-up, operation may pinch the discharge valve and potentially the flow may be lower than minimum flow and results in pump damage. To avoid that, we are thinking to locate the minimum flow before the discharge check valve however we are not convinced without basis from standard. Hopefully any experts could enlighten me.

 

thanks.



#2 Art Montemayor

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Posted 29 April 2019 - 09:37 PM

The best way to describe exactly what you propose to do with the location of your minimum pump flow nozzle as it relates to your pump piping is to simply draw a detailed sketch - just as any pump operator or engineer would do.

 

A detailed drawing is an international language that is understood by everyone (if it is done correctly) and we don't have to struggle with the English language --- or any other language.

 

Please take the time and draw one, attaching it to your next post.  Our members will understand your proposal and query much better and respond without having to ask a lot of questions. 



#3 breizh

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Posted 29 April 2019 - 10:10 PM

Hi ,

You should understand the reason for the check valve and the risk for back flow (siphoning effect) ……. To me there is no much option.

About the minimum flow how will you manage it ? valve, orifice, ..

As Art pointed out a sketch will save words which  includes the location of valves you have been considering and a simple SOP .

my view .

Breizh

Attached Files


Edited by breizh, 30 April 2019 - 09:31 PM.


#4 fallah

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Posted 30 April 2019 - 11:36 AM

Hi,

 

No special code/standard dictates such location to take a branch off for pump minimum flow line...other than potential for check valve failure to get stuck in closed position. Hence such take off location would mostly be a safety issue...



#5 ccwlun

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Posted 02 May 2019 - 07:53 PM

Dear All,

 

Thank you for the valuable replies.

 

Please see the sketch as attached.

 

We are thinking to tie-in the low-flow protection line (recycle line) before the check-valve because operationally, the discharge valve will be adjusted during start-up for fine-tuning though normal design where low-flow tie-in is located after the check-valve. However, I can't find it from API 610 for this configuration although the design seems valid practically. Hence, I am seeking for experienced experts for more advice. 

 

Thanks.

 

Note: Please assume that check valve is not required at the low-flow protection line.


Edited by ccwlun, 02 May 2019 - 07:54 PM.


#6 ccwlun

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Posted 02 May 2019 - 07:55 PM

Sorry, I missed the attachment earlier. Please see from here.

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