Finally, the weekend and I can do fun stuff! In this case, we've been trying to perfect our ability to deal with deuterium and hydrogen at very high (5 9's) purity, and not be stuck with just the one tank we get from the supplier. In the case of the very pure H we recently got, they didn't want to even sell us the tank, so we want to repackage it and get out of the lease as well.
Bill Fain found all this stuff - some very nice aluminum tanks originally for medical oxygen or firemen breathing apparatus, and some correct valves for hydrogen. The tanks were pretty "used" and nasty looking, while the valves were threaded for a larger tank, while the oxygen tanks have a thread "all their own". Obviously a little machining and fab has to be done to get to the goal.
Since Joe Jarski does precise machine work better than I, and this is a place where that really matters, Joe did the valves.
Luckily, these had enough extra meat on the stems to allow this. Now they fit perfectly. "Like buttah". He won't brag, so I'll do it for him.
Then I took a bunch of those ratty tanks, and cleaned them up on my lathe:
I now have to make a little punch/die to make the teflon gaskets - many were lost before the tanks got to me, and we found (the hard way) that viton isn't good enough -- slow permeation by the hydrogen. I will also be detail-cleaning the insides of these tanks, and then baking under vacuum before doing the gas transfers, to keep at least 4-5 of the 6 nines purity of the gas we have.
It's not easy to get these outgassed -- takes a long time through the valve. About a week of heating (not too hot!) and pumping each is required. Since we're working with hydrogen, I may put a few pellets of lithium into each to act as getters for residual air and water as well.
We like working with the small tanks for a variety of reasons. For one thing, in case of accident, you don't lose too much, or create the possibility of an enormous explosion. It also makes it much easier to keep track of how much you're using (or wasting). Further, those interested in getting some now have a way (or will shortly) though these can't ship legally at this point. They are mostly out of hydro for one thing, not rated for flammable gas and so forth. But better than nothing, and we've already jumped through the paperwork hoops to get the gases in the first place.