Co2 cylinders # Vs. ft²

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I'm looking to finally add a Co2 cylinder to my setup. I've been running flux core up until now.I called airgas, and they gave me prices for 40ft² and 80ft² cylinders. ($175 80ft² + $51 Co2)I called a LWS, and they told me they only had 20# cylinders. ($120 5/yrs + $20 Co2)Now I'm really confused. Isn't liquid Co2 around 9ft² per lb? Why would I buy a 80ft² cylinder for almost twice as much as a 20# one? Am I missing something here?I've searched the forums, but haven't found the answers I'm looking for. It seems every thread is either ft² based or # based. Thanks In Advance!My welder:Century 180 Wire feed welder.
Reply:A 20 # water capacity cylinder should hold approx. 50 cu.ft. of gas @ about 2200 - 2400 psi.
Reply:I think airgas was confused, and was quoting you something like C25 and not CO2.CO2 is sold by the pound just like propane (ok, propane is also sold in gallons, but NOT cubic feet).Gases such as Argon and C25 are sold by the cubic foot.  By my math, I get around 8.2 cubic feet per lb of CO2.  You're close enough to get a good comparison though.I calculate around 165 cubic feet of CO2 in that 20# cylinder (some other numbers I've seen online put that closer to 175 ft^3).Both because of the higher pressure tank, and the more expensive contents (namely the argon part), C25 is considerably more expensive than CO2 per cubic foot.BUT, you may be happier with C25, and will probably get better results with it, depending on what you're doing, so maybe Airgas was just making some assumptions on your behalf.Last edited by rlitman; 04-27-2011 at 11:02 AM.
Reply:Thanks for the replies guys. After some digging I had also come to the conclusion that Airgas quoted me on c25. Most of my welding is going to be on 1/8" to 1/4" steel, with some sheet metal (20-22 ga).I'm guessing I'm really gonna be pushing my luck penetration wise with my little century 180 running c25. Any opinions?My welder:Century 180 Wire feed welder.
Reply:I'm a big Co2 fan Ebola, but...I think your 180 would like the 75Ar/25Co2 for your needs, Co2 likes a little more voltage at any given wire speed and really likes a power supply with more headroom (reserve power).To run Co2 well in the 90amp range usually takes a 250amp class machine, the "bigger the better" to quickly clear the short circuit condition.(edit) if the small power supply is an inverter my advice probably won't apply.MattLast edited by Matt_Maguire; 04-27-2011 at 12:44 PM.
Reply:I too am a big fan of CO2.  Just a little more spatter to clean but much cheaper than C25.  If your fit up is good and snug a quick shot of PAM will make the spatter beads come off very easily with a putty knife and your ready to clean and paint.  Just my .02. I have both in my shop.BobI'm spending my Kids inheritance, I dont like him that much anyway!!!!!!Enuff tools to do the job, enough sense to use em.Anybody got a spare set of kidneys?  Trade?
Reply:I run CO2, I own my 20 pounders, and they cost me 12 bucks to have filled.Disclaimer; "I am just an a$$hole welder, don't take it personally ."
Reply:1# co2= 8.74 CF20x 8.74 = 174.80 cfI used Co2 in our little Lincoln 100HD with no problems and the SP135I'm running C25 in my MM211 and MM252 and don't see any HUGE change so for me I would buy the Co2 20# tank since it is more economical.Ed Conleyhttp://www.screamingbroccoli.com/MM252MM211 (Sold)Passport Plus & Spool gunLincoln SP135 Plus- (Gone to a good home)Klutch 120v Plasma cutterSO 2020 benderBeer in the fridge
Reply:OK, I called airgas back. The woman I spoke to this morning did give me the price for Ar/Co2 mix.For an 80ft³ C25 cylinder I'm looking at $175 for the cylinder, $51 for refills, and 50% off the initial fill. About $200 total, and around 3 hours of welding time.For a 20# Co2 cylinder I'm looking at $140 for the cylinder, $25 for refills. About $160 total, and around 7 hours of welding time.This sounds about right doesn't it?Now I would need to buy a Co2 regulator, as mine is a CGA580 reg. Total initial investment back up to around $200 for Co2.To top it all off, an 80ft³ cylinder won't fit on my cart under my workbench. A 20# Co2 cylinder won't fit in my cart without hacking it up, so Now I'm looking at a 15#.My welder:Century 180 Wire feed welder.
Reply:You can buy the adapter at Airgas to run your Regulator, about 10-15 buxEd Conleyhttp://www.screamingbroccoli.com/MM252MM211 (Sold)Passport Plus & Spool gunLincoln SP135 Plus- (Gone to a good home)Klutch 120v Plasma cutterSO 2020 benderBeer in the fridge
Reply:If you can find an old CO2 fire extinguisher cheap, you can usually trade that in for a same sized CO2 cylinder and save a bundle.