If anyone is actually serious about small-scale experimenting with fairly high pressures possible, a proper pressure vessel should be used, rated high enough. One way to DIY a small tank with internal access, is with pipe fittings. The cheapest is probably galvanized steel or black iron. An assortment of say, 2 inch NPT nipples and fittings can make all sorts of containers and plumbing line attachments. A plug or cap at one end can serve as the access door to the chamber. It won't be hermetic, but that's not necessary for this situation. You can use electrical feed-throughs - like the kind for RF assemblies with bypass caps and such. They can be mounted and sealed easily in gooped threaded holes. I think feed-throughs and almost every standard connector type are available in hermetic sealed versions, but fairly spendy. I always save these kinds of things from salvaged stuff, and have a pretty good assortment in stock. I also save any junked metal semiconductor packages like stud-mount rectifiers and TO-3 etc transistors, for their metal-glass seals. I especially have a lot of axial lead end-caps from old shot or damaged hermetically sealed capacitors - they are easily un-soldered from the body tube. It's best to of course have the smallest practical volume for minimal energy storage. If there's any doubt about the vessel, whether it's home-made or commercial, you can add safety margin by packaging it up with wrapping materials and outer enclosures to absorb energy and trap the chunks if something does go wrong. I recently built a refrigerant recycling machine for R134a from junk parts. I needed to proof it and adjust the safety relief valve, so I let the compressor pump air to 450 PSIG where I set the cracking level. The most dangerous part is the receiver/oil separator, a small cylinder about 10-15 cubic inches, made of thin sheet steel. It's a real thing, rated 300 PSIG, but used and maybe forty years old. I set it up with the cabinet top in place, pushed back slightly to access the relief valve, while still covering the receiver, and I wore safety goggles and earmuffs. It worked out beautifully, and once it was proofed, I could safely pump it to around 250 PSIG for leak testing while all opened up (still with protective gear on). Ed

Hi At least in terms of the original question about sealed oscillators, I would avoid going to crazy with the pressure. The cans are pretty robust, but you can indeed crush them. The glass to metal seals on the wires going into the package are always a question mark in terms of ruggedness. Test to destruction might be the goal, but if not, keep the pressure below about 100 psi (and probably better, 50 psi). Bob > On Dec 13, 2022, at 7:12 PM, ed breya via time-nuts <time-nuts@lists.febo.com> wrote: > > If anyone is actually serious about small-scale experimenting with fairly high pressures possible, a proper pressure vessel should be used, rated high enough. One way to DIY a small tank with internal access, is with pipe fittings. The cheapest is probably galvanized steel or black iron. An assortment of say, 2 inch NPT nipples and fittings can make all sorts of containers and plumbing line attachments. A plug or cap at one end can serve as the access door to the chamber. It won't be hermetic, but that's not necessary for this situation. > > You can use electrical feed-throughs - like the kind for RF assemblies with bypass caps and such. They can be mounted and sealed easily in gooped threaded holes. > > I think feed-throughs and almost every standard connector type are available in hermetic sealed versions, but fairly spendy. I always save these kinds of things from salvaged stuff, and have a pretty good assortment in stock. I also save any junked metal semiconductor packages like stud-mount rectifiers and TO-3 etc transistors, for their metal-glass seals. I especially have a lot of axial lead end-caps from old shot or damaged hermetically sealed capacitors - they are easily un-soldered from the body tube. > > It's best to of course have the smallest practical volume for minimal energy storage. If there's any doubt about the vessel, whether it's home-made or commercial, you can add safety margin by packaging it up with wrapping materials and outer enclosures to absorb energy and trap the chunks if something does go wrong. > > I recently built a refrigerant recycling machine for R134a from junk parts. I needed to proof it and adjust the safety relief valve, so I let the compressor pump air to 450 PSIG where I set the cracking level. The most dangerous part is the receiver/oil separator, a small cylinder about 10-15 cubic inches, made of thin sheet steel. It's a real thing, rated 300 PSIG, but used and maybe forty years old. I set it up with the cabinet top in place, pushed back slightly to access the relief valve, while still covering the receiver, and I wore safety goggles and earmuffs. It worked out beautifully, and once it was proofed, I could safely pump it to around 250 PSIG for leak testing while all opened up (still with protective gear on). > > Ed > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe send an email to time-nuts-leave@lists.febo.com