Old Argon bottle for emergency air?

If you have a Tig welder you could use it a shielding gas.

ARGON GENERAL FACTS:
Colorless, odorless, tasteless and non-toxic, argon (Ar) is a noble gas that comprises 0.93% of the earth's atmosphere. Argon can provide an inert and clean environment free from nitrogen and oxygen for annealing and rolling metals and alloys. In the casting industry, argon is used to flush porosity from molten metals to eliminate defects in castings. In the metal fabrication industry, argon is used to create an inert gas shield during welding. Argon is frequently blended with carbon dioxide (CO2), hydrogen (H2), helium (He) or oxygen (O2) to enhance the arc characteristics or facilitate metal transfer in Gas Metal Arc Welding (GMAW or MIG).

Because 100% argon can be used to TIG weld all metals and thicknesses you only need one type of gas in your shop to handle all of your welding projects. MIG welding aluminum is different than welding steel when it comes to shielding gas requirements. For aluminum, 100 percent argon is the gas of choice.

Most welding supply shops don’t want anything to do with a gas cylinder that did not originate from them. But that’s not to say it’s not worth a try.