Determining Tubing Cv
Determining Tubing Cv
(OP)
I'm designing a manifold and wanted to find out my flow rate through a valve, check valve and length of tube. I have the valve Cvs and appropriate formulae, does anyone have a good source for tubing Cvs of tubes in the following sizes: 1/4", 3/8", 1/2", 3/4" and 1"?





RE: Determining Tubing Cv
Although I have never heard of a "tubing" Cv, that doesn't mean that someone couldn't come up with one. However, based on the principles and reasons as to why the Cv principle was developed, I doubt you will find one.
Basically, the Cv principle is used to rate the maximum flow capacity through a device - a valve, for example. A tube doesn't qualify because you have stated it's principal flow determining characteristics: the I.D., the length, the configuration (is it looped? pig-tailed? straight?)
Until you identify the flow characteristic features, you can't determine an equivalent Cv. Can you be more specific as to where you obtain this tubing Cv criteria? Why would you want to apply it to tubing when you can resort to the conventional method of analyzing fluid flow through tubing: the Darcy-Weisbach relationship?
Art Montemayor
Spring, TX
RE: Determining Tubing Cv
I have used some Swagelok data on determining the expected pressure drop over a length of pipe and correlated that back to an effective Cv, but the values I've calculated seem low, lower than my valve Cv of the same tube size. This doesn't make sense.
RE: Determining Tubing Cv
1) Set up the normal dP equations for a line for your lengths
2) solve to find flow rate for a dP of one psi
This equals Cv. Your methode does not make sense unless you know both ID and (equivalenth) length of your pipes.
Best regards
Morten
RE: Determining Tubing Cv