Helium valve seal
Helium valve seal
(OP)
Problem: I need to seal and then open quickly a 30 inch orfice. It is to hold 0.18 psi helium at -45 deg C with minimal leaks. My best sealing material I beleive is silicone. How could the valve best seal helium? a flat gasket design? o-ring design? other?





RE: Helium valve seal
RE: Helium valve seal
looking theoretically at your problem (no further details than given - especially on opening/closing mechanism) the best sealing material could be butyl rubber as stated above.
Best sealing constructions for flanges or lid-like sealings would probably be o-ring in groove engineered to fit together (dept and width of groove to give just enough room for the O-ring to compress and fill grove at given conditions - (this is an art) - counterface flat).
If you really want to put money into quality the O-ring would be of PTFE to cover (more than required) of the lower temperature range or FEP - construction (rubber covered by PTFE).
Note: a lot of cheaper solutions exists, both for form and material just check what is reasonable result and cost for you.
Ask a top quality sealing producer/supplier!