No, get the script then take it to the gas supplier and see what their policy is about filling. Odds are they don't fill but swap, and won't even look at the hydro date. so you'll lose any money you spend on a hydro the minute you turn it in.
Or forget the script and send your buddy with the DAN card in with the bottle, a lot of times you can get emergency O2 with just that, if they check at all, as long as you act like you know what you are doing.
It's always worth calling first to see what their policy is, just so you don't get some idiot tank-nazi trying to confiscate your tank on some nutty grounds. Tell them you bought an old O2 set for dive emergency use, and want to get it filled, and want to know what it will cost. If they say they only swap, tell them its out of hydro and see what they say. If they say you'll have to pay for a hydro, try another shop, or bring it in a week or two later and just don't say anything and see if they notice.
When you swap tanks, the fill charge includes a reserve for hydros, since the company takes care of it not the tank owner so it doesn't really matter to them, but some shops will try to charge you extra for the hydro just for the hell of it.
BTW, putting aviator's O2 into a medical tank constitutes unauthorized manufacture of a prescription drug in the eyes of the FDA, so most suppliers won't do it unless you remove the medical O2 labels, and often not even then. And many suppliers these days charge extra for filling your own tank. Far easier to find a shop that will swap it out as a med tank.
Oh, and if its an alu tank, don't let them swap if for a steel one
I'll get it hydroed and then call my PCP for the script.
Thanks everyone [/B]