Straight co2

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Hello!What are the advantages and disadvantages of mig welding with straight co2 vs 75/25? I don't think I would ever be welding the very thin gauges like 20-24 (probably never even 18 gauge).
Reply:Outside of being cheaper to run CO2 I don't know of any. It's a lot more violent of an arc, and a lot more spatter.Sent from my Pixel 6 Pro using Tapatalk
Reply:CO2 gets downright COLD as it exits the tank, so it has a greater cooling effect on the MIG gun.  Better duty cycle and/or higher amps for shorter periods.

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Reply:I use it exclusively.  Some modern machines like my Multimatic 200 have programming specifically for CO2 to help with the spatter, although honestly spatter has never been an issue for me with CO2.  I use it in the MM200 with solid wire, and I use it in Suitcase 12RC's running off of either XMT304's or TB325's with ESAB 7100 Ultra Dual-Shield wire.CO2 generally gives you more penetration as well as being cheaper to run.  Because it's a liquid changing to a gas as it exits the tank, you get more runtime per tank volume than you'd expect.  So since most LWS's won't allow you to own much larger than an 80cf tank, you get more bang for your buck with CO2 when talking customer-owned tanks.  The tiny tanks of mixed gases like 75/25 are positively highway robbery-priced for what you get, and if you get a large enough tank to get better pricing, now you're paying an annual tank lease at $70+ per year.I haven't bought or run any 75/25 for what must be nearly a decade.
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Originally Posted by cbourbeau32

Hello!What are the advantages and disadvantages of mig welding with straight co2 vs 75/25? I don't think I would ever be welding the very thin gauges like 20-24 (probably never even 18 gauge).
Reply:If you doing a lot of welding and cost is a factor then CO2.If doing little or cost not a factor then 75/25 has a smother weld. There are other factors to type of wire you are using.  In my shop I had CO2 and could mix gas too. But cost was a factor as all my work was Quoted. A bottle of CO2 will last almost 3 times longer and cost less too.Dave

Originally Posted by cbourbeau32

Hello!What are the advantages and disadvantages of mig welding with straight co2 vs 75/25? I don't think I would ever be welding the very thin gauges like 20-24 (probably never even 18 gauge).
Reply:The other thing to consider is that some machines weld great with straight CO2 and others don't. My Hobart Handler 190 was an example of a machine set up from the factory to run well with straight CO2. Machines with adjustable inductance settings can usually be tweaked to run pretty well with straight CO2.Miller Multimatic 255
Reply:1 pound (liquid Co2) equals roughly 8.5Cuft of gas. So, a 20# tank of Co2 has about 175 Cuft of gas in it. unless you have a regulator for Co2 already, you will need a CGA320-CGA580 adapter, and make sure you have the nylon washers!. Pure Co2 runs cooler than mixed gases, a good start is to add about 3 volts to your settings
Reply:It cost me $19 to fill the 200 size tank with CO2 and the same size in 75/25 is $78. That as well as the CO2 lasting about 4 times as long makes it a no brainer for me. If you are having excess spatter issues then you aren't keeping your nozzle close enough to the weld. I build a lot of furniture that has to be perfect and if it was a problem then I would change but it just doesn't.
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Originally Posted by Bob

It cost me $19 to fill the 200 size tank with CO2 and the same size in 75/25 is $78. That as well as the CO2 lasting about 4 times as long makes it a no brainer for me. If you are having excess spatter issues then you aren't keeping your nozzle close enough to the weld. I build a lot of furniture that has to be perfect and if it was a problem then I would change but it just doesn't.
Reply:I happen to recall, as a CO2 source you can use a CO2-bottle that pub-owners use to pressurize the beer-pump.That would be the cheapest method.Do not know about separate fittings to connect and legal issues eventually.oldwelderman
Reply:One other thing with CO2, If you weld in a cold winter shop issues can arise. More than a few times running straight CO2, I had to get out my heat gun/ hair dryer and mount it next to the regulator because the blasted thing was freezing and cutting off flow.HTP  Pro Pulse 220 MTS (Anniversary Edition) 1962 Idealarc Tig  300 300 1974 Idealarc Tig  300 300  1988 HF Power Mig 150  2015  Lotos Ltpdc2000d plasma/Stick/TIG    Victor 100 torch, 200- 210 Oxy/Acet gauges
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Originally Posted by 455dan

One other thing with CO2, If you weld in a cold winter shop issues can arise. More than a few times running straight CO2, I had to get out my heat gun/ hair dryer and mount it next to the regulator because the blasted thing was freezing and cutting off flow.
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Originally Posted by cbourbeau32

Bob, what welder do you use?
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Originally Posted by tbone550

So since most LWS's won't allow you to own much larger than an 80cf tank
Reply:If cold inside the shop the regulator ice will form. But you need to use a lot of gas.Dave

Originally Posted by Jack Ryan

Speaking of freezing CO2, I saw this image the other day - for a regulator/heater combination.Jack
Reply:Forgot to mention one thing...some people find Co2 a little harder to dial in compared to mixed gas.Check out my bench vise website:  http://mivise.comMiller Syncrowave 250DXMillermatic 350P with XR AlumaProMiller Regency 200 with 22A feeder and Spoolmatic 3Hobart Champion EliteEverlast PowerTig 210EXT
Reply:CO2 is different and most charts are for mix gas. I like mix gas but I do not like the cost and some types of flux core wire is only rated for CO2. I think come down to how must welding you plan to do. My self I could use 60 pounds of co2 a week. This would be almost 530 cf of mix gas a week. Dave

Originally Posted by G-ManBart

Forgot to mention one thing...some people find Co2 a little harder to dial in compared to mixed gas.
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Originally Posted by oldwelderman

I happen to recall, as a CO2 source you can use a CO2-bottle that pub-owners use to pressurize the beer-pump.That would be the cheapest method.Do not know about separate fittings to connect and legal issues eventually.oldwelderman
Reply:The higher the C02 content, the higher energy the gas. It will also affect the shape and depth of the weld kernel. C02 weld pool will freeze faster than a mixed gas pool.Lincoln 275 SquarewaveLincoln SP 250
Reply:Here in Japan, CO2 is very common in the average job shop. Running 25/75 costs around 6x more. I run a heated regulator that plugs into the standard 100v outlet, and never have issues with icing.