C25 argon cylinders pros and cons and shelf life question

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Hi all,I am new to this forum.I have been welding with a flux core wire and finally decided toupgrade to C25 (Argon/CO2 mix).I have questions about equipment that I need to buy:1)  I am debating whether to get 40 cu ft or 55 cu ft cylinderThese two cylinders differ in design, not just in size.  40 cu ft hasa flat bottom, while 55 is spherical.  Also, 55 cu ft cylinder istaller, but has smaller diameter than 40 cu ft.Does the fact that 55 cu ft cylinder has a spherical bottom make itless prone to leak?   (since there is no seam around the bottom)Or  the chance of leaking around the bottom is negligent compared tochance of leaking at the valve or around the valve?On the other hand, a 40 cu ft cylinder can stand upright on its flatbottom.So, what are the pros and cons of each?2) What is the shelf life of C25 mix?I would rather go for a bigger bottle that would serve me for years,but if it leaks out, than bigger bottle is a waste of money for me.How long can I expect  40 cu ft or 55 cu ft cylinders to hold gas? Ifthey leak relatively fast, I might need to downgrade to a 20 cu ftcylinder.Thank you.
Reply:All these high pressure tanks are seamless and should have a flat bottom that would allow them to stand on there own.  Just like women some bottoms are more rounder then others and I've never seen a LWS store cylinders laying down. In any case you should have these cylinders secure at all times by some type of chain and/or rack. You should look at getting as big of a cylinder as you can handle/afford because larger cylinders are cheaper to fill when you base it on price per cubic foot of gas. Example around where I live a 40 cf tank of Ar was $30 to fill but a 160cf tank was $40 for a refill.The gas should never go bad and there should be no reason for a cylinder to leak. How much welding do you plan to do? Most of he time when some talks about losing gas is when they forget to shut off the valve on the tank and they have a leak in there line somewhere.
Reply:At the pressures involved, a seam in the bottle just isn't really possible.  Both of those cylinders are forged from a single piece.As for the shape of the bottom.  It has been known for centuries that a rounded bottom bottle resists deforming under pressure.  With the bottom domed out though, it is impractical to store, because it cannot stand up.  Champagne makers discovered that an bottle with an inverted dome in the bottom would resist having the bottom blown off by the pressure as well as a domed bottom, and could also stand on its own, and the rest was history.Scientific American once ran an article on the physics of a soda can's bottom inverting (you've probably seen one where the bottom popped out if it got dropped or too warm . . .), and the pressures needed to do that were incredibly high.  There is no practical benefit for a bottle being an "outie".A welding cylinder's inverted dome bottom is over an inch thick (actual dimensions depend on the metal used, etc.), and is several times the wall thickness.  It is very much like a soda can in that respect.Anyway, I for one would never get a cylinder with a domed bottom.  It is just too inconvenient to store.  Then again, I've never seen a 55CF cylinder, and the 40CF, 60CF and 80CF cylinders available locally are all "innies".  I've only seen a bottle like you described for use as supplemental aircraft oxygen, and then the bottle was permanently mounted, so standing up was not an issue.Now for your shelf life question.Helium is quite leaky (it is the leakiest substance known to man actually), and can escape just about anything over time.  Still, a valve in good working order should be able to contain helium for many decades.Argon, CO2, C25 etc are all nowhere near as leaky.  Their valves are tested with helium in the factory, and if doesn't leak that, it won't leak anything else (if your valve is still good, and actually closed tightly).Your biggest shelf like issue will be that a cylinder needs to be retested every 6 (or possibly 10) years.  You can continue to use it after the certification has expired, but will need the re-test to have it filled (and for a few other purposes, like transportation through a tunnel, etc).
Reply:As said above, there seamless. I would'nt worry about it leaking out. Keep your valves tight when not in use and you should should be good. I would buy the biggest you can get. I have a 80cf for my home shop tigging needs and it seems to last ok but it all depends on how much your welding, regulator setting and such... As said the refills on the bigger cylinders are almost the same cost as the smaller ones.Ya gotta spend money to make money!
Reply:>> All these high pressure tanks are seamless and should have a flat bottom that would allow them to stand on there own. Here is the 55 cu ft tank. I don't know how they expect it to stand on the welding card because it clearly has the rounded bottom.http://weldingdirect.com/gascyl55cfar.htmlMy local supplier carries bottles similar to the one above. They do not carry 40 cu ft bottle.Personaly, I think that 55 cu ft bottle is ugly, but I need it to hold gas, not to look at it.I am doing very little welding - like fixing something around the house once a year. Mostly I need to weld sheet metal. This is the main reason why I want to switch from flux core to MIG -- flux core often burns through the sheet metal.With the amount of welding that I do I expect that 55 or even 40 cu ft bottle to last me for years.
Reply:Originally Posted by welderShaneAs said above, there seamless. I would'nt worry about it leaking out. Keep your valves tight when not in use and you should should be good. I would buy the biggest you can get. I have a 80cf for my home shop tigging needs and it seems to last ok but it all depends on how much your welding, regulator setting and such... As said the refills on the bigger cylinders are almost the same cost as the smaller ones.
Reply:There is a huge economic benefit to larger cylinders. Let me give you an example of my local prices.To refill/ swap:40 cu/ft - 30 dollars80 cu/ft- 36 dollars300 cu/ft- 52 dollarsSo you'd have to refill a 40 size bottle over 7 times for a total of 210 dollars to equal the gas in my 300 size bottle for 52 dollars.Kevin- Springtown, TexasTruck:Chevy cab/ chassis 1 ton dually, big block and flatbedMiller BobcatVictor cutting rigTool boxes crammed full of stuffShop:Millermatic 250Lincoln 135Lincoln 225AC tombstone
Reply:Originally Posted by ymg200>>Here is the 55 cu ft tank. I don't know how they expect it to stand on the welding card because it clearly has the rounded bottom.http://weldingdirect.com/gascyl55cfar.html
Reply:the gas in cylinders will never go bad. i picked up some 300 cu ft cylinders of O2 that are from the 50's that are perfectly good, and still had full pressure. as far as bottle sizes the way that i do it is 80 cu ft for mobile welders and 300 cu ft for stationary welders.Dynasty 200DXPassport plus w/ spoolmate 100victor 315c oxy/(act and prop)Miller digital elitemilwaukee power tools
Reply:rlitman,I found the similar 55 cf bottle on Ebay:http://cgi.ebay.com/55cf-Welding-Tan...-/200457576945The description says:"The rating on this tank is a DOT 3AA 1800, which means it has a working pressure of 1800 psi."Is it good or bad that the pressure is lower than in most common cylinders?My welder is Campbell Housfeld 105 (the discontinued model). It came with preset gas regulator that has no gauges. It is preset to 30 cfh.Does lower pressure of the 55 cf bottle affects me anyhow?
Reply:I have two 330cf tanks of C25. I switch them out when one gets empty (They last a LONG time). It costs $60 including Tax at my LWS to exchange a 330cf tank.Make sure you open the valve all the way and not just crack it open. It seals open and closed but can leak between.Other than that leaving the tank on with a leak in your system is the biggest problem as mentioned earlier. I check the connections VERY WELL because I have stupid attacks and leave the tank on sometimes and it does not leak out but you have to be sure your system is tight.I was out of commission for a year after a wreck and my tank was still full even though it was open. I use teflon tape at all joints and it works great.
Reply:Originally Posted by ymg200rlitman,I found the similar 55 cf bottle on Ebay:http://cgi.ebay.com/55cf-Welding-Tan...-/200457576945The description says:"The rating on this tank is a DOT 3AA 1800, which means it has a working pressure of 1800 psi."Is it good or bad that the pressure is lower than in most common cylinders?My welder is Campbell Housfeld 105 (the discontinued model). It came with preset gas regulator that has no gauges. It is preset to 30 cfh.Does lower pressure of the 55 cf bottle affects me anyhow?
Reply:40 and 60 cubic foot bottles are really tiny, expensive to fill per volume and don't last long.  The minimum size i have are 80cf.  All the compressed gas bottles up to 150cf are close in outside diameter, about 8", the difference are the heights.  Then the 200 and up bottles go to the next up diameter, about 9", with different heights.  The biggest size I like to move around in a portable application is a 150cf.  The 200's and above are only good for the shop.  I use 80's and 125's on the truck and a mix of 150's and 250's in the shop.  The 330's are monster back breakers to move, I don't like them much.MM350P/Python/Q300MM175/Q300DialarcHFHTP MIG200PowCon300SMHypertherm380ThermalArc185Purox oaF350CrewCab4x4LoadNGo utilitybedBobcat250XMT304/Optima/SpoolmaticSuitcase12RC/Q300Suitcase8RC/Q400Passport/Q300Smith op
Reply:...That green cylinder looks like the aircraft (or personal oxygen) supplemental tank...usually mounted in frame or clamping system..  That blue cylinder looks like a Nitrous Oxide cylinder for auto racing....they have round bottom as they are usually mounted near horizontal...with the valve facing front of vehicle...so acceleration keeps liquid contents near the siphon tube...and NOX usually 900-1200 PSI depending on temperature...as is C02.  NOX and C02 usually sold in pounds per cylinder...not PSI...and with NOX and C02...vapor pressure will be near max. until contents depleted....only way to know amount in the cylinder...weigh it, then add that to the tare weight stamped on the cylinder near neck/valve....same deal for Acetylene....  As for gas 'going bad'...I've used cylinders with 25+ years on the last fill-up...and also rented/leased Oxygen cylinders stamped as old as 1934...as long as they pass the pressure test...no problem....Dougspair
Reply:Originally Posted by Ayers GarageThere is a huge economic benefit to larger cylinders. Let me give you an example of my local prices.To refill/ swap:40 cu/ft - 30 dollars80 cu/ft- 36 dollars300 cu/ft- 52 dollarsSo you'd have to refill a 40 size bottle over 7 times for a total of 210 dollars to equal the gas in my 300 size bottle for 52 dollars.
Reply:I have a 40 cuft bottle and ive been thinking about buying a 3000 psi hose and some fittings to fill it from my 300 cu ftanyone ever do this?
Reply:AMC,The 40 price is exchange at WardThe 80 is exchange price at Tractor SupplyThe 300 price is Phillips. In the last few years I've gotten to where I basically only shop at Phillips. They treat me very well over there, where other places have been harder to deal with. I bought some of my equipment there and I buy all my steel there every week. I won't say anything bad about Ward, but they have frustrated me a few times. It's a father/ son team over there. The son does me right, but the father will sometimes give me completely opposite answers than the son does.I do get my 300 cu/ft oxygen bottle that I run on my truck filled at Ward fairly often though. He charges me 32 dollars and does it while I wait so I continue to use his service on that.Kevin- Springtown, TexasTruck:Chevy cab/ chassis 1 ton dually, big block and flatbedMiller BobcatVictor cutting rigTool boxes crammed full of stuffShop:Millermatic 250Lincoln 135Lincoln 225AC tombstone
Reply:Originally Posted by AMC724I have a 40 cuft bottle and ive been thinking about buying a 3000 psi hose and some fittings to fill it from my 300 cu ftanyone ever do this?
Reply:[QUOTE=ymg200;450929]>> All these high pressure tanks are seamless and should have a flat bottom that would allow them to stand on there own. Here is the 55 cu ft tank. I don't know how they expect it to stand on the welding card because it clearly has the rounded bottom.http://weldingdirect.com/gascyl55cfar.htmlI think you are mistaken. All welding cylinders will stand upright. There is a picture of a 65 cf oxygen (high pressure, same cylinder as used for shielding gases) cylinder included in this post. The smallest cylinder I would recommend is 92 cubic feet. I use a 251 cubic foot cylinder for my MIG machine only because I haven't found a 330 cubic foot one yet. As has already been posted, really a lot of the cost of refilling is labor, so the larger cylinders are relatively much cheaper to refill since you will do so much less often. They all will fit on the back of nearly any welding cart. The cart takes the weight. The only reason for small cylinders is if you have to manually carry them up stairs to a job.metalmagpie(new to this forum) Attached Images
Reply:The oxygen cylinder on my torch cart is 125CF, and the acetylene is 140.  They're movable, but not something I'd like to have to carry around on a regular basis.  If you've got a truck, then larger tanks may be ok.  For a hobbyist with a small car like myself, that's about my limit.BUT, more important, is what is available.  At my LWS, 60CF argon tanks are the easiest to get exchanged, and they sometimes have 80CF tanks, so that's what I've got.  I suppose I would get 125's if they had them, but anything larger is just too annoying for me (even if they always have the larger sizes available).
Reply:My guys use 300s for everything.  In the field, they go through 6 bottles a week (3 man crews, 2 12 hour shifts), so smaller is not really an option.  In the shop, I have gas hard piped and we get 5 6-packs a week, but that is just first shift only.  It all depends on what your usage is.
Reply:please, never do this, the danger outweighs any benefit, best Ralph
Reply:I like to keep 2, 330cfm tanks in the shop, the partially depleted one I use in shop on my non-mobile Syncrowave until empty and the newly filled one I use for filling the 22 & 80cfm tanks that are on my van for my portable TIG, I had a transfer hose with a gauge made through Terrace supply (I don't recall the cost), and when I'm done with a job, I just top them off and load them back into my van (you need to keep in mind the tank date and re-certify when necessary). I can't imagine how much this system has saved me over the years as I do a lot of small stainless repairs and a larger tank isn't practical to lug around.
Reply:Originally Posted by rlitman  Champagne makers discovered that an bottle with an inverted dome in the bottom would resist having the bottom blown off by the pressure as well as a domed bottom, and could also stand on its own, and the rest was history.
Reply:Get an 80 for home owner portability!A year ago I was going through an 80 every 3 to 4 months. This year, I haven't been doing much mig welding, hence I have the last 80 from last year still on the cart. As long as valves is all the way open and all the way closed. Don't over tighten! They don't leak.As far as mixed gasses going bad. If a tank has been in storage for a long time, the gas molecules will separate. Roll it on the floor for 5 minutes to redistribute the gas mix. All the components posted so far talk about O2 bottles being super old, not mixed gasses.Hmm just realizing how much we weld at work, i go through a 7780 cubic foot bank in 8-10 weeks, an 80cu would only last me 2-3 days