I think OxyHacker has explained it better then I could have. When He bought the booster of Ebay, the person he bought it from was boosting 02 for a re-breather also, so it was 02 cleaned all ready, as well as used for 02
I do know that he changed some o-ring's etc, and went through it himself , so he didn't go on someone's else's word that it was o2 ready.
As far as filling, I been there when we filled our alum 30's and 40's with pure o2, and as Oxyhacker has mentioned, as long as you fill them slow, and keep them cool, your fine. As far as filling 02, I was concerned as well, as he does fill tank's to 4500 psi with 100% o2, but since my last post, he only is filling now to about 3600 psi, in a tank that's rated to 3442 , So I'm ok with that. Reason why , is we use a transfer whip, and bring the bigger tank 100 cf , filled with 3600 psi 02, and we transfer the 02 into the 13 cf tank's , and we can get a bunch of fills for the re-breather's that way, so we never have to go in for air fills on trip's etc.
It's been working out really well for us, as long as all the usual precaution's are taken for handling pure 02.
Good to see ya, I didn't know you were a SB staff