In VA, and possibly all states? the largest the "customer" can easily own is 80 cuft, it's about 40" tall or so, and 6 or 7" diameter.
They said if I want a larger one I can rent it.
Or if I really want to own a large one I should buy two, or more, and expect to wait a few weeks for a refill. They will send one out for the refill and I can use one, then swap. If it needs to be tested or inspected it's on me. And if I damaged it, say strike an arc on it by mistake, it then won't pas inspection, and I have to buy a new one.
With the 80 cuft and smaller they just exchange them, and they keep up with the inspections and test when needed. I own two, and usually have them exchanged two at a time, but if I am getting low and in the middle of a job or before the weekend I'll get the one empty filled to get me through.
Grigg