[T3] Air compressor ?

Jim Adney jadney at vwtype3.org
Sun Jul 26 17:44:21 PDT 2020


One thing to keep in mind is that copper tubing comes in different wall 
thicknesses. The thinner wall stuff is not suitable for any of the ferrule style 
sealing methods, because the wall will just collapse rather than being stiff 
enough for the ferrule to bite into it and seal.

I learned this lesson many years ago, when i was working on a small system 
that had to be helium leak-tight. I could make a leak tight joint at one end of 
the tube, but as soon as I did ANYTHING to the other end, the movement 
would open up a leak on the first end. The thing I was working on was a 
network of maybe 20 connections in a couple square feet, so until I switched 
to heavy wall copper, I was just chasing one leak after another.

I finally found recommendations from Parker and Swagelock regarding the 
min. wall thicknesses for various diameter tubes that could be reliably 
sealed. Look here:

https://www.swagelok.com/downloads/webcatalogs/EN/MS-01-107.PDF

Read the section about gas service on page 2, as well as the chart on page 
7 regarding copper tubing. The note at the bottom of page 7 seems to 
indicate that the minimum wall thickness for air in 1/2" copper tubing would 
be 0.049".


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Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA
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