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Pressure Control Valve Operation Query

pressure control valve control valve control flow pressure

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#1 rs20170808@gmail.com

rs20170808@gmail.com

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Posted 02 June 2021 - 02:38 AM

i have a pressure control valve which is for keeping pressure at its downstream to 350 psig and is sized for 22 mmscfd flow

 

the pressure at inlet in normal operation is 400 psig

 

however, lets say in a case the pressure at inlet is < 350 psig,,,,in that case will the control valve go maximum or fully open?

 

the cases for control valve sizing are: 

 

max 22 x 1.1 = 24.2 mmscfd, pinlet = 400 psig, poutlet = 350 psig

normal 22 mmscfd, pinlet = 400 psig, poutlet = 350 psig

min 22 x 0.5 = 11 mmscfd, pinlet = 400 psig, poutlet = 350 psig

 

in case we encounter a flow lower than 11 mmscfd at inlet, what will be the impact on control valve



#2 latexman

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Posted 02 June 2021 - 07:02 AM

however, lets say in a case the pressure at inlet is < 350 psig,,,,in that case will the control valve go maximum or fully open?

 

in case we encounter a flow lower than 11 mmscfd at inlet, what will be the impact on control valve

 

< 350 psig inlet, the CV eventually goes wide open

 

< 11 mmscfd, it depends solely on downstream pressure.  350+ psig the CV starts closing and 350- psig the CV starts opening.



#3 fallah

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Posted 02 June 2021 - 08:02 AM

i have a pressure control valve which is for keeping pressure at its downstream to 350 psig and is sized for 22 mmscfd flow

 

the pressure at inlet in normal operation is 400 psig

 

however, lets say in a case the pressure at inlet is < 350 psig,,,,in that case will the control valve go maximum or fully open?

 

the cases for control valve sizing are: 

 

max 22 x 1.1 = 24.2 mmscfd, pinlet = 400 psig, poutlet = 350 psig

normal 22 mmscfd, pinlet = 400 psig, poutlet = 350 psig

min 22 x 0.5 = 11 mmscfd, pinlet = 400 psig, poutlet = 350 psig

 

in case we encounter a flow lower than 11 mmscfd at inlet, what will be the impact on control valve

 

Hi,

 

At the inlet pressure less than 350 psig, the valve will go to full open position...



#4 Pilesar

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Posted 02 June 2021 - 08:55 AM

The real minimum flow for most control valves is 'zero'. The control valve sizing cases are supplied to choose a valve that operates near the middle of its range (perhaps 30% to 70% open) where the flow is expected to be controlled. The middle range of valve opening gives the most predictable behavior and best control. Near the full open and full closed range of the valve, the control response suffers and the valve may need to move more during disturbances to try to keep the process variable at set point. The additional movement may result in rapid valve wear and unsatisfactory control performance. In the real world, control valves often operate well outside of the range of their design cases. 





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