CO2 vs C25 weld quality

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I find myself in a tank situation where I need to trade up for a bigger tank.  The tank I need to trade in is a 25# CO2 tank for beer making.  Its 8" in diameter and around 30" to the valve top.  It is totally full, so I'd like to use it up first.  It is for Migging steel with a MM200.  There's an adapter on eBay for $15 to allow this tank usage with the standard Argon gauge.  The question is, will there be any major difference in weld quality between straight CO2 vs. c25?I'm basically doing small projects and hobby work.  No Xray quality welds needed here.  I plan on filling the next tank with C25, as I've read it is optimal for migging steel, and I've been very happy with my results with it so far.  ThanksLast edited by Drf255; 10-13-2011 at 06:29 AM.TA Arcmaster 300CM3XMT 304S22P12 suitcase feederX-Treme 12VSOptima pulserTA161SMaxstar 150STLHypertherm PM45OP setupStihl 020AVP, 039, 066 Magnum
Reply:CO2 will give you slightly more penetration than C25 will and will cost less per cf. C25 however will give you less spatter and a nicer bead appearance.As far as "quality", I'm not sure if you are talking visual appearance or a sound weld. Both gasses will produce a sound weld if done right. C25 will have a nicer bead appearance of the 2 gasses however, if that's what you are looking for. A better understanding of what you are trying to accomplish would help..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:It isn't really your question however note that that carbondioxide is a liquid inside the tank and vaporizes to gas in a manner similar to propane.  My tank contents were sold as pounds not as cubic feet.  Maybe someone else can say approximately how many pounds of welding wire it would take to empty that tank.  I kind of doubt that tank is too small.
Reply:Also your weld properties are reduced a bit with Co2 and oxidation in the weld itself is increased. Comparing Co2 and C25 to me with E70 wire is much like comparing 6010 and 7018 electrode.The little MM200 and Co2 were pretty much a mainstay of shops fabbing with miscellaneous iron for years, it has a sweet arc to it.When Co2 is used it's mostly because it's cheap, fast and tolerates crappy conditions.Matt
Reply:Thanks for the info.  So it sounds like a small tank can hold alot more gas when it's pure CO2 because it changes state.  "Quality" to me means a strong weld that won't break.  I'm only doing projects for myself.TA Arcmaster 300CM3XMT 304S22P12 suitcase feederX-Treme 12VSOptima pulserTA161SMaxstar 150STLHypertherm PM45OP setupStihl 020AVP, 039, 066 Magnum
Reply:CO2 Density = 1.977 g/L (gas at 1 atm and 0 °C)1 pound = 453.59 grams1 liter = 0.0353146667 cubic feet25lbs = 11339grams and expands into 5735 liters of gas.5735 liters = 202 cubic feetSo your 25lbs CO2 cylinder holds roughly the same gas volume as a large cylinder of C25.  Or for the same size cylinder the liquid CO2 expands into roughly twice as much gas.  Assuming I did the math right!Dynasty200DX w/coolmate1MM210MM VintageESAB miniarc161ltsLincoln AC225Victor O/A, Smith AW1ACutmaster 81IR 2475N7.5FPRage3Jancy USA1019" SBAEAD-200LE
Reply:Originally Posted by Drf255Thanks for the info.  So it sounds like a small tank can hold alot more gas when it's pure CO2 because it changes state.  "Quality" to me means a strong weld that won't break.  I'm only doing projects for myself.