CO2 are often owned and can be filled quite easily. Mix gasses, is a little more involved. Still, sometimes with customer owned cylinders, you have to wait to have them filled.
I think Todd should clarify that when he talks about a 50 amp AC/DC welder, he is talking about a 50 amp input 230 volt machine typically in the 200-300 amp range.
Arc Weld, you are right I wasn't thinking when I posted that I should point out that is the input not output.
Todd