I have an applications and need som
I have an applications and need som
(OP)
I have an applications and need some assistance in validating a proper ball valve Cv is sufficient for the application:
Application:
Natural Gas
62,000 lbs/hr Min
68,000 Lbs/hr Max
MaxP = 560 PSIG
MaxT = 770 Deg F
Diff P = 560 PSI
Density = 0.044
MW = Min (16) Nor (17.5) Max = (19)
The Pipe size is 8" schedule 40
I believe an 8" full port ball valve is sufficient that has a manufactures published Cv of 9300
I have ran a few calculations but the math does not appear to be correct and I am hoping someone can help explain to me how to calculate Gas flow in LBS per hour to determine if the Cv of the valve is sufficient. I came up with a required Cv of 3328, which would allow me to use a smaller valve. However I just want to learn how to properly size the valve and validate my calculations.
I was trying to convert to SCFM first but again I am confused how to determine if the 8" valve is properly sized.
Thank you for your time and input.
Have a great day !
Jack
Application:
Natural Gas
62,000 lbs/hr Min
68,000 Lbs/hr Max
MaxP = 560 PSIG
MaxT = 770 Deg F
Diff P = 560 PSI
Density = 0.044
MW = Min (16) Nor (17.5) Max = (19)
The Pipe size is 8" schedule 40
I believe an 8" full port ball valve is sufficient that has a manufactures published Cv of 9300
I have ran a few calculations but the math does not appear to be correct and I am hoping someone can help explain to me how to calculate Gas flow in LBS per hour to determine if the Cv of the valve is sufficient. I came up with a required Cv of 3328, which would allow me to use a smaller valve. However I just want to learn how to properly size the valve and validate my calculations.
I was trying to convert to SCFM first but again I am confused how to determine if the 8" valve is properly sized.
Thank you for your time and input.
Have a great day !
Jack





RE: I have an applications and need som
You don't say what that is.
Try this sitem (scroll down for gas non critical flow)
https://www.engineeringtoolbox.com/flow-coefficien...
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: I have an applications and need som
RE: I have an applications and need som
Like I said, valve CV needs to have some sort of differential pressure otherwise you're dividing by zero somewhere.
How did you arrive at a required Cv of 3328?
I've got lost as to where to go next in this thread.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: I have an applications and need som
The schedule pipe is 40. I was attempting to use 1 lb-mole/MW) X 359.05 to determine SCFM and then 0.0177 to determine the actual Cv requirement.
RE: I have an applications and need som
Your density seems unusually low for natural gas at 560psig, 770degF - I get approx 0.85lb/ft3, assuming z=1.
Use the closing dp for the torque to be developed at the ESV actuator, not for the Cv of the valve.
BTW, how does this gas get to 770degF?