Ad-Hoc Tank Blending Risk

[Johnoly]

When I was filling, I never trusted what was inside a customer's tank (even my regulars). Air or otherwise cause if the % or gas is wrong, the filler has the liability for what's in the tank. If I had too many rush tanks to do, then I'd drain the rush tanks and didn't bother with the pre-check. For anyone who's ever done shop fills, I don't know anyone who wouldn't catch 100% (or high %) O2 in a tank. I also would ban the customer from future fills. I'm not going to hold the liability for an Ox-Tox'd diver. Furthermore, Us tank fillers PRIDE ourselves on hitting the requested % EXACTLY on the number >> So we watch you analyze and see how well we did our mixing. So I'll catch it then. Also if you try to leave without testing, then that's a red flag and I'm going to look closer. Tank fillers are not stupid, but we've seen some crazy stuff (like obvious dremel hydro dates & print your own VIP labels) Take your tank somewhere else, I'm not filling it.

 

[Johnoly]

....O2 is released into a closed fill whip, the temperature in the whip will instantly rise to about 1500 degrees due to pressure change. ...

1500 degrees?

I understand there are all different kinds of setups for a fill station. But we really don't want to dump the gas inside of that 4-6 ft long fill whip> mostly because it takes to long to depressurize and we don't have time with a long line of tanks to fill. I also don't want a whip flying about wildly cause a shutoff handle was left open. I have enough problems with old burst disks letting go. Almost every fill whip has a line shut off handle right next to the DIN/Yoke/Bleed assembly. This allows me to just depressurize about 4 inches of line very quickly so I can remove the assembly from the tank valve and put it on the next tank. If your bandit tank full of O2 was hooked up, it would only go 4 inches and that's not enough gas volume to heat up the whip (and certainly not 1500 degrees). There also are backflow preventers at different points in the fill station. Some by the bank bottles, some by the compressor and some by the whips > just depends how it was designed because there's plus's and minuses to everything.

In the end, bringing in a bandit tank full of O2 for an air fill will not have a good ending. The mix will be off, or your tank will be drained or you'll get banned from future fills.