In Lexington, KY, you can't get your new shiny tank filled, but if you give them your new empty tank, they will sell you a full rusty one (but check the pressure before you leave the counter, because they might sell you an empty one, and it's hard to prove it if you come back later). Hard to give up the brand new tank the first time you go there...but when you return the rusty tank for full rusty tank, there is no pain, you don't care what it looks like, as long as it's full.
At least these is no rental charge...I don't use a lot of gas, and it doesn't cost me if I go a year between refills.
Yes, in most states they would be liable if it was a tank's fault. They have to be approved and tested by DOT as they are pressure tanks. I think they have to look inside every year and hydro-tested every 5, at least scuba tanks have that requirement. If they pass the tests then the filling company is pretty much off the hook. Transman
I was treated once with a supposedly medical oxygen tank for cluster headaches that almost killed me, learned the tank was filled by a local welding shop and was contaminated. But thank God, I wasn't a hundred feet below in water when that happen, could quickly rip off the mask. I wasn't born paranoid, but sure made that way by these bad experiences. Learned later that only a few are approved for medical oxygen, this was like 25 years ago. I did visit my local tank supplier, that place was filthy.
Here in Washington, you can get your own "owner tanks" filled but it can take up to a day or two if they are busy or you can rent one from the company for usually around $5 a month and just exchange it for a full one and pay only for the contents of the bottle...you only pay for renting the bottle once a month. The problem with the renting is that there are basically 2 major gas companies in WA and one won't fill the other one's bottles. If you travel a lot like I do, it's a problem because a lot of times there will be one company in a town, but not the other. Owner bottles are the way to go. Either co will fill them.