Pressure Drop in Compressed Air Line
Pressure Drop in Compressed Air Line
(OP)
I'm trying to calculate the pressure drop (psi) in a compressed air line at an outlet flow of 100 cfm. Because it's compressed air, I believe I need to use a mass flow calculation and not volume flow. All the information I look up uses volume or velocity to find friction losses. It seems the velocity would decrease as a function of distance upstream from the outlet. I have 165 ft(including equivalent lengths for elbows and tees) of 1/2 inch copper pipe.
Thanks
Thanks





RE: Pressure Drop in Compressed Air Line
It has equations for working in both volumentric or mass flow, it doesn't really matter since the equations handle the expansion factor for compressible flow and the conversion between mass and volume.
For your 1/2 copper piping, is this piping or tubing? And if tube, what wall thickness?
RE: Pressure Drop in Compressed Air Line
Here's the website for ordering a Crane 410 (which, IMHO, everyone who works in fluid flow ought to own): http://www.vervante.com/crane/ It is relatively cheap (US$33), available in both English and Metric, and well worth it. And NO I DON'T WORK FOR THEM (and never have.)
However, having said that, while Crane 410 does have a discussion on working with compressible gases, it doesn't provide a lot of information (and looking at their bibliography, what information they have is rather dated). So unless you just want a "rough guess", you might want to get something a bit more accurate.
Patricia Lougheed
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Forums"
RE: Pressure Drop in Compressed Air Line
Regarding things like steam tables, and pipe dimensions, I typically find the 100 year old tables to be virtually identical to the much newer versions, and freqently accurate to more decimal places.
RE: Pressure Drop in Compressed Air Line