O2 cylinder

In my professional capacity as a nondestructive test engineer, I was
peripherally involved in the successful effort to get DOT approval for
acoustic testing of high pressure cylinders carrying gasses on truck
trailers, as well as for acoustically testing composite liquefied
natural gas cylinders used in automobiles. I have also personally used
acoustics to inspect pressure systems used in Mach 14 wind tunnels that
involve pressures up to 60,000 (yes, sixty thousand) psi of air. Those
were some crazy thick walled pressure vessels...made the 16 inch rifles
on the battleship New Jersey look puny!

In the United States pressure vessels must be certified to either DOT
or ASME standards. If a pressure vessel to be used in the USA does not
have either DOT or ASME certification, it is illegal to use it, much
less to fill it. For example, check out Michelin, Continental,
Bridgestone, Dunlop or Pirelli tires - they all have a DOT approval for
USA usage, even though they aren't made here. Yes, tires are considered
to be a pressure vessel - so is your hot water heater, for that
matter.

Sorry, Hartley, you're going to have to buy another oxygen cylinder
if you want to be legal.

-John