mig - co2 vs co2_argon mix

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I'm wanting to switch from co2/argon mix to straight co2. Have a few questions that I need help with:1) Supplier suggested 20 lb co2 bottle. Said it would last 3 times as long as my 125 cu ft co2/argon mix. Cost about $20 to fill the the co2 bottle........about $40 to fill the co2/argon mix. Is he correct about how long it would last?2) Thinking of getting (from Craigs List) a large o2 bottle and swapping it for a large co2 bottle.  How long could I expect this bottle to last compared to the 125 cu ft co2/argon bottle?  Cost to refill is about $32.My welder is a Miller 130 and portability is not a problem.  Have a stick welder for the heavier stuff. I have been told about additional weld spatter resulting from using co2.Comments and suggestions would be appreciated.
Reply:He's giving you the right info. You shouldn't have any real spatter issues until you push past the 130 to 140 amp range. The Co2 needs a bit higher voltage for any given wire speed and I imagine that is noted on the chart with your Miller.On the large cylinder, the 50lb is about all I really want to handle (these are filled with liquid and get heavy fast).MattLast edited by Matt_Maguire; 07-15-2010 at 08:03 PM.
Reply:A previous post covered the choice between these gases quite well - see "Converting to Shielding Gas..." posting at http://weldingweb.com/vbb/showthread.php?t=4210In that posting, gmn109, gave the CO2 lbs to cubic feet factor you are looking for.> Each pound of C02 is about 8 cu. ft @.1234 lbs of C02 per cu. ft. of gas equivalent.> A 20 lb liquid C02 cylinder is equivalent to about 160 cu. ft of gas in a larger tank.I hope that helpsRick V 1 Airco Heliwelder 3A/DDR3 CTC 70/90 amp Stick/Tig Inverters in Parallel1 Lincoln MIG PAK 151 Oxy-Acet
Reply:You will also need to get an adapter to change the reg to fit the CO2 bottle since they are different threads. The LWS guy can get you what you need if he doesn't have it in stock..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:Originally Posted by no_arcI'm wanting to switch from co2/argon mix to straight co2. Have a few questions that I need help with:1) Supplier suggested 20 lb co2 bottle. Said it would last 3 times as long as my 125 cu ft co2/argon mix. Cost about $20 to fill the the co2 bottle........about $40 to fill the co2/argon mix. Is he correct about how long it would last?2) Thinking of getting (from Craigs List) a large o2 bottle and swapping it for a large co2 bottle.  How long could I expect this bottle to last compared to the 125 cu ft co2/argon bottle?  Cost to refill is about $32.My welder is a Miller 130 and portability is not a problem.  Have a stick welder for the heavier stuff. I have been told about additional weld spatter resulting from using co2.Comments and suggestions would be appreciated.
Reply:OOPs, I got it upside down too, it's the gas cost per pound of weld applied that is 1/3.Last fills at Praxair were 50# Co2 ($19.23), 336Cf  C10 ($57.33) and 95Cf C25 ($20.66). I think that 95 is supposed to be a 120... Gonna have to do some checking.Matt
Reply:Never used straight C02 before and I also have a question. I heard when using straight C02 that you need an electrically heated regulator to keep it from freezing. Is this true?
Reply:No, but what can happen if you are welding with a new cylinder for long periods is the pressure will build on the low side of the regulator after you stop the gas flow. I just look back when I stop welding and if I see the low side going up I just bump the trigger once or twice. On my automatic the Co2 regulator is a Co2 flowgage with a small heat exchanger before the diaphram (it will sweat like crazy sometimes but never frosts).Matt
Reply:Originally Posted by madkaw284Never used straight C02 before and I also have a question. I heard when using straight C02 that you need an electrically heated regulator to keep it from freezing. Is this true?
Reply:Learn something new everyday. Thanks guys