Well the connection between the Swagelok parts and the Subaqua Products parts
was more problematic than I expected. The top picture to the right, P1, is the
Swagelok part 400-7-4RG. The second and third pictures, P2 and P3, are of the
SAP 3084 300bar Elbow. I wanted them to connect but the Swagelok part lacks a
cut out for a SAP sealing ring on the shoulder as it expects one at the
Unfortunately the part I wish to screw into this is shaped as P4 (SAC 1625) and it will not sandwich a washer as it has a cut out for the conical adapters of the hoses as in picture P5.
I started by trying to sandwich an O-ring regardless of not having a cut out but that popped out at about 80 bar so, after some experiments I contacted SAP who tried to solve the problem by making the washer shown in P6 with a conical end to go into the screw in and a flat side to mate up against the Swagelok fitting. The part looked right so I assembled it finger tight and put some gas pressure on it. It hissed. I gently tightened the fittings. It hissed less, less, less, more. OH DRAT. Tightening it up and applying pressure had rendered it P7.
There was a delay but when I discussed it with SAP we came to the conclusion that we needed metal and settled for Brass. They made the part shown in P8 and I sandwiched an O-ring below the flat side and spannered it up. I let the presure on gently - no hiss so I assembled the other side and tested it. Chuff-phut, Chuff-phut we were pumping gas.
We fixed it but it does seem ironic that the biggest problem was nothing to do with pumping reactive gas at high pressure they were just the usual run of the mill problems you get connecting any two dissimilar systems.
The only other snag is that a 770bar pump will destroy a 275bar gauge in moments if you shut the valves in the wrong order. <sigh> Such is life.
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