Here, air liquide is the distributor. Bottles are exchanged. I had an acetelyne given to me. 15 years ago. I exchanged it without issue. Bought a filled oxygen outright. Was expensive, but i have torches now.
This seems to be a fairly recent change--last 10 years?. I deal with "Ox arc" here. I took my bottles in--not fully empty, as I was concerned about the cert date and did not want to get stuck with the high cost of pressure cert. They told me they don't hang that on the customer anymore, with "owner" bottles. I've forgotten what all is "owner" the tiny 20/40 O2, the 80 O2 and what we used to call a 60 acet. Around here I either 122 or 150 bottles were or could be owner. Some used to be "lease" and some used to be "rent." Way back in the 70's there were PISSED customers who had had what they thought were 99 year leases on bottles, and "I guess" a merger/ buyout resulted in them becoming "20" year leases----and many were "up." We lost a few customers, over that deal.
