Because why the f not, right? I inherited some medical oxygen 14 cubic foot cylinders from my wife's aunt. I turned some of the empty ones into torch bottles by getting them hydro tested and replacing the med valve stem with a CGA 540 which is pretty much the standard oxygen valve stem for torching and filling them with welding grade oxygen. But the other ones are still full. Picked up a medical regulator off eBay for like $10.