What are the true points to measure on a tank to estimate size?

admin

I have two mystery tanks.   I see lots of charts about sizes but I was curious where the height measure really comes from.  Do you measure the flat part where the valve screws in to the base?  Do you measure the top of the valve knob to the base? or do you measure from the top of the cylinders protective screw on top to the base?  I guess I missed the "Cylinder Measuring 101" class on the forum.  Point me in a nice direction and I will go.The reason why I am asking is that I just bought two mystery tanks off of a guy for $20.00 (based on $6.00 per 100lb scrap metal I thought I might only lose about 60% if they are useless but if not I get a great reward).  The tanks have NO markings on them at all.  I need to check but it seems they are O2 and possibly Argon.  I may post some photos shortly. Now if only the local gas company will take them in as a trade for filled cylinders!
Reply:Post up the ruff dimensions, dia. and height. Not all tank mfgs make the tanks the exact same size so it's a bit of a guessing process. There are several charts that have been posted. I'll see if I can find them. If so I'll PM you the links.The tank should have some markings on them. At the very least they should be stamped with the DOT info and hydro dates on the tank shoulder. The hydro date will tell you if they need to be tested. Often on exchange the LWS will just charge you the test fee and swap the tank if it's out of hydro. Also the valve will have numbers stamped on it proceeded by CGA. This tells you the valve type, and what gas it would hold. CGA 540 is O2, CGA 580 is Argon, 75/25, helium etc.This info plus picts will help determine the sizes..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:Cubic foot capacity, ie "size" is also related to the psi the cylinder is rated to contain.for example a 300 psi cylinder may be the same physical dimensions as a 3000psi cylinder but not the same "size".It would be very difficult to get those filled without any markings on them.  Too many unknowns.Miller 185Lincoln Weldanpower 225Lincoln 225 buzz boxCheap-o C&H 110v (my first welder)
Reply:Stamping and/or tagging standards have been in place in the US for sooooo long that a pressure tank with no markings is virtually unheard of. Either those were made in the 1800's or they came over on a boat from a country of origin unknown. I'm wondering, if you did take those in to an independent agency for the 1st time ever inspection and testing, just what the heck would they use as a starting point? What would be the initial gauge? "Looks like" a 3000lb psi tank or "looks like" a 300lb psi tank ?  A lot of folks might be willing to offer a guess but few are going to start pressurizing based on their own best guess when it comes time to put up or shut up. Scrap??
Reply:Tanks are a battle field implement, or a device for holding non pressurized liquids.Please use the correct nomenclature.
Reply:Well I got to take a look at them today in the light.  There are no obvious markings and it is possible that they were ground off at the top of the cylinders shoulder and if so it was done well.  The tall one has a CGA 320 valve for CO2 and the shorter one has a CGA 580 for Argon or other inert gases.   The height of the tall one is 56.5" (top of the cap), 51" (where valve screws in) or 50" (where the shoulder converts to a threaded part).  The width is 8.5".  The shorter tank is 49" (top of the cap), 42" (where valve screws in) or 39" (where the shoulder converts to a threaded part).  The width is 7".I am attaching photos and check out the vertical lines running in the shorter tank.  If I did not know better, I would say it was made in the 80's due to the stamp on the bottom of the cylinder.   The other one has 3-4 numbers on the bottom (I think they are numbers) but it is a bit rusty and I probably need to wire brush that area to see better.So what do you think?   Would a company like National Welders take these in as a trade to a filled set of tanks?   Also, I have a small Lincoln 100 MIG which I am currently using a 25%CO2 Argon mix but I was not sure if I should have a CO2 tank (I heard it helps to give a deeper weld) for the future?  I plan on getting about a 200-220 Amp MIG like a HTP Mini Mig. Attached Images
Reply:and the other tank Attached Images
Reply:Does this help?reference_cylinder_information.pdfMM200 w/Spoolmatic 1Syncrowave 180SDBobcat 225G Plus - LP/NGMUTT Suitcase WirefeederWC-1S/Spoolmatic 1HF-251D-1PakMaster 100XL '68 Red Face Code #6633 projectStar Jet 21-110Save Second Base!
Reply:The CGA 580 cylinder is most likely an 80cf or 100cf depending on the psi rating and mfg. There should be stamped markings on the black shoulder area. In one pict it looks like someone may have taken a sander to the shoulder. This could be because the tanks failed hydro and were scrapped. They usually XXXXX over all the markings when they fail so that the tanks can not be reused. The other possibility is that the original stamps were light and someone sanded the area to try and read the markings and then repainted the tank and the marks disappeared again. I've seen both. At worst all they can say is "NO". I would just take it in, not say anything and see what happens. Some counter guys don't care. As long as they have a bottle, they'll let the guys who fill them at the main place deal with it.I'm not all that familiar with CO2 cylinders. The rough size would lead me to say it's 200 cf, if it was for O2 or argon. I don't have any use for CO2 so it's not one I'm as familiar with. I do know that they often use O2/Argon tanks that don't measure up on hydro as CO2 after remarking them. That may be whats happened to this one. One this size may be an issue. Many places don't exchange cylinders over 150cf unless it's one of theirs and you have a lease with them. They don't consider cylinders this size to be "owner" units, only rentals. Again, try and see what they say.Good luck..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:I had about 5 more images but in as much as I thought they were resized, the forum did not upload them.
Reply:Originally Posted by accentphotography. . .So what do you think?   Would a company like National Welders take these in as a trade to a filled set of tanks?. . .
Reply:Yeah ... I may just waltz them by, put them on the dock and say "hey I need an exchange" and leave it at that.  You never know.  Bottom line for me is that I want a collection of welding tanks at a reasonable price.  I think most of them above 80CF are in the $240-$300 range.  What is funny is that you are still buying a used tank that could be from 1920.    Thanks for the chart.  I am posting this one the I like as it has the heights and widths as well. Attached Images
Reply:AP - Thanks for posting the nice chart.BTW  - CO2 is filled  by weight. Originally Posted by accentphotographyYeah ... I may just waltz them by, put them on the dock and say "hey I need an exchange" and leave it at that.  You never know. . .
Reply:I just recently bought a 150 cf for C25. It was $265.00 out the door full. The 80 Cf would have been $235.ish or around there. Forget exactly what he said. Almost as much any way.
Reply:I saw the Airgas here send one guy back down the road with his tanks in hand. His had a half inch of flake rust on the very bottom and still had cobwebs in the valve openings and chicken gum on the handles. Straw and leaves dangling off them every where. Other than that I've never seen them really give them a second glance.
Reply:That one tank definantely looks like someone ground off the stampings, we had Hydrogen in the bigger 200-300 cf bottles for use in a hydrogen cooled generator, while standing around during a purge one day I got to looking at the bottles and saw dates as far back as 1919, there were numbers stamped all over the top of one of the bottles. It was to the point where they weren't going to be able to put any more numbers on there.“Life is not a journey to the grave with intentions of arriving safely in a pretty well-preserved body, but rather to skid in broadside, thoroughly used up, totally worn out and loudly proclaiming ... WOW! What a ride!”
Reply:Well, Monday is coming and I cannot decide to try to change the tank or spend the day with my wife since it is our wedding anniversary.  Hmmm ....