Joe Pfeiffer wrote:

Bruce L. Bergman writes:

There's one size up that is normally Owned and not Leased, but they
can be harder to get filled. The one place that deals with them a lot
is the Thoroughbred exchange system at Lowes and other DIY stores, but
they do charge a lot more for the convenience.

Could this be a local thing where you are? the only tank exchange I've
ever seen at my Lowes was propane....

Probably pretty regional. The Lowe's here doesn't have anything but LP
that I've noticed, but the Depot across the highway from them has a full
array of industrial gas exchange, Oxy, Acet., Argon, CO2, etc. all in
cages out front next to the LP cage. The Tractor Supply nearby also has
the noted Thoroughbred exchanges. I just deal with my local Airgas
branch, also in the same area as they have the other stuff I need like
LN2, TIG filler, Plasma consumables, etc.