I have a problem that I can't turn down a bottle that is either cheap or free EXCEPT: I currently have 13 owner bottles
If the bottle is a 300 or 250 cubic foot bottle that has the marking of a welding supply on the ring. If present then you can keep it. The 300 or 250 cubic foot has to be a slick ring or without thing stamped or raised letters on the ring.
The most common bottle that I run across that is either cheap or free is a 180 cubic foot. I don't care if ring is slick or with stamping or raised letters on it. The 180 bottle is considered a owner bottle at any welding supply that I have dealt with. This has included IOC, Airgas and Praxair.
Any bottle that is smaller than 180 cubic foot I never never mess with.
Most gas supplies will exchange a 180 to 250 cubic foot bottle with money to boot. If you are not close to a gas supply you might think about a larger bottle. Now when it comes to 300 CF bottles make sure that your gas supply has owner 300 CF bottles. (Mine has a limited supply. Sometimes I have to wait for them to fill.)
Just make sure that you are getting a slick ring see attached Image.
Acetylene bottles are a horse of a different color. I have four of five of them. I can never tell what is a owner bottle or a company owned. I will usually watch out for heavy stamping that states a name of a company.
At the time of exchange the test date is ten years for the last stamped date on the bottle. This has been the same for acetylene or high pressure cylinders. They usually charge $17 to $25 for retest. I have seen them just take them without retest and needing to be retested. But this it the times that I come in with 7 to 8 bottles.
You can exchange any owner bottle that is a oxygen to a sets say 75-25 of equal size without paying any difference other than the gas price. I have done this a couple of times when I need mig gas. My supplier doesn't care.
I currently have three welding gas bottles 90-10, 75-25 and one straight argon. I currently find my self welding with the 90-10 mix more the the 75-25. Double pulse.
One of the biggest things is to shop around for supplier to supplier for better gas prices. Remember you have an owner bottle that can exchange anywhere.
The highest I have ever paid is $133 for a bottle that was because they were 300 CF bottles that were owner bottles. Most of the time it is about 50 dollars or less. Garage sales are the best places to get them. I have found them on market place but usually the ones I see are company owned bottles that they can't get rid of and are trying to stiff the unknowing.
P.S.
The 300 CF bottle I converted to a mix gas from a oxygen bottle. I had to pay for retest and a new valve. Only because it was 300 CF owner bottle and they didn't have any at the time.
