Jump to content



Featured Articles

Check out the latest featured articles.

File Library

Check out the latest downloads available in the File Library.

New Article

Product Viscosity vs. Shear

Featured File

Vertical Tank Selection

New Blog Entry

Low Flow in Pipes- posted in Ankur's blog

1

Sizing Control Valve For Pump Recirculation Line


4 replies to this topic
Share this topic:
| More

#1 Butterfly

Butterfly

    Gold Member

  • Members
  • 81 posts

Posted 19 January 2021 - 03:01 PM

Dear all. I am dealing with a centrifugal pump with two main operating scenarios, fisrt one is pumping of 100 m3/h, and second one pumping 300 m3/h. This is flow of liquid going to storage. Flow of 300 m3/h corresponds to maximum pump flowrate, and 100 m3 is due to flowline limitations. Each scenario has a different destiny.

 

Pump minimum flowrate is 110 m3/h. I have one question regarding minimum flow valve sizing:

 

Normal/maximum valve flowrate would be 110 m3/h. What about minimum? In the second scenario (normal flow of 300 m3/h), the valve will be (or could be) closed. In first scenario, I need 10 m3/h going through the valve, so I can think of setting that value as valve minimum flow. The problem is that maybe we find out (design is not  finished yet) that I can pump, let's say 105 m3/h. Then, I could have problems with the miniflow control, cause I sized the valve for 10 m3/h minimum, and now I need 5 m3/h, valve would tend to open very litttle, and I could have pump cavitation problems. Is this reasoning correct?

 

Will I have a limitation in my design, cause I cannot pump anything between 101 and 109 m3/h. This seems weird to me, but I have to fix a value in order to size the valve.

 

So, how can I set "minimum flow of minimum flow valve"? Should I set 10 m3/h and add notes on the operating manual (do not operate between 101-109 m3/h)?

 

Thanks for your help



#2 Bobby Strain

Bobby Strain

    Gold Member

  • Members
  • 2,941 posts

Posted 19 January 2021 - 04:26 PM

You don't necessarily need exactly 110 m3.

 

Bobby



#3 Butterfly

Butterfly

    Gold Member

  • Members
  • 81 posts

Posted 19 January 2021 - 05:48 PM

I need anything higher than that, and a set point to determine when I need the minimum flow to open. I am using 110 m3/h for that "set point". With a different value, the reasoning would be the same, I think. If I choose 120 m3/h, and size the valve 80% open for 120 m3/h, which flowrate should I use for sizing minimum % opening of the valve?



#4 breizh

breizh

    Gold Member

  • Forum Moderator
  • 4,893 posts

Posted 20 January 2021 - 01:44 AM

Hi,

Your control valve should able to operate within the range 20 t0 80% of the max flow rate  .

"

When sizing control valves, a general rule of thumb noted in many engineering publications is to size the valve such that it operates between 20 to 80% open at maximum required flow rate. It is also recommended to have the minimum opening no less than 20% to provide a safety margin at the minimum flow rate required. "

 

Good luck

 

Breizh 



#5 Butterfly

Butterfly

    Gold Member

  • Members
  • 81 posts

Posted 21 January 2021 - 04:17 PM

Thanks to you both






Similar Topics