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Re: Cascade Storage Banks

Posted: Tue May 14, 2019 9:21 pm
by antique diver
Who ya calling old?

Re: Cascade Storage Banks

Posted: Tue May 14, 2019 10:09 pm
by rx7diver

This is good to know. Thanks.

I learned a while ago another reason for opening the tank valve first: When decanting/transfilling high octane gas (say, FO2 >= 0.80), I was taught to open the tank valve first--that is, to open the lower pressure tank first--to minimize the chance of adiabatic heating (is that what it's called?) and possible combustion/explosion that can result if a lot of high octane gas moves too quickly.

If your "scuba" cylinder is an oxygen deco bottle (and you know it contains nothing but O2 because you tested it) and your cascade system contains pure O2, there is almost zero chance of contamination. So, my earlier caution doesn't apply in this case.


Re: Cascade Storage Banks

Posted: Wed May 15, 2019 9:37 am
by SurfLung
antique diver wrote:
Tue May 14, 2019 9:21 pm
Who ya calling old?
Did I say "Old"? I meant really smart handsome guys... :)
- It's funny I would just say "old guys"... It was guys who have been around long enough to have experienced exactly what was happening to me when they were filling tanks in the olden days. Namely, I was filling tanks and sometimes swapping the whip to an empty tank I would look up and see the pressure gauge registering 3000 psi when I was supposed to be filling an empty 1800 psi tank... Sort of un-nerving at first... Thinking I over filled the 1800 psi tank. But the 3000 psi was all trapped in the fill whip. The vintage tank valve seats were sealed shut on an empty tank even though the knob was twisted open.
- But nowadays, when I open the tank valve first, this never happens anymore! Thanks to old guys who are smart, and handsome!