Welding with CO2

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Righty Tighty

Righty Tighty

Blame it on the dog
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I do a fair amount of welding at my shop, and until now, I've used CO2/Argon (75/25), TIG, and stick. The 75/25 works great and makes beautiful beads, but my bottles are the smaller 60 cubic foot size so they go fast and it's expensive to fill.

I picked up a larger K size bottle of CO2 for a great deal and started putting down some beads to learn the difference. The first welds were fine -- not as pretty as 75/25 but they had good penetration. Further on into the project, the arc started acting like I had a bad ground.....popping and wouldn't stay consistent. Double checked my ground clamp, good to go.

I looked at my gauges and increased from 10 CFH to 15. Seemed a little better, until the problem happened again. Increased from 15 to 18 CFH. Better, and then problems again. I look at the gauge again, and the needle is slowly increasing in flow. 30.....35....40 CFH. I watched it slowly go all the way around until it pegged the needle.

The gauges are CO2/Argon gauges that I used for 75/25.

Seems like something in the regulator is bad and I'm heading to the welding supply shop when they open, but I thought I'd ask if anyone here has experience with welding with CO2, and has had this happen before.
 
I know of no such problem. CO2 is pretty much all I use. Most my welding is around the place structural, and I have trouble seeing the weld anymore, so much of it is not pretty. CO2 works as good as anything for me. More spatter, I don't care. Way way cheaper, especially as CO2 is a liquid, so bottle last a very long time.

I don't / cant do bodywork, so very little of my "work" is of that nature
 
Okay, thanks for your input. I’m leaning towards a bad gauge and/or regulator. I’ve read that CO2 can damage (from the cold temperature) your gauge if the gauge isn’t meant for CO2, but this is a CO2/Argon gauge.
 
I asked a welding instructor I used to teach with what to expect using CO2 instead of 75/25 and he said the following:
It will be fine. Usually takes a little more voltage. But often runs a little hotter than the mixed gas. A -6 wire would be better than a -2 wire. The -6 has additional anti-oxidizing additives and the -2 is for flat or horizontal welds. He also said it may have more spatter to use just co2 and that is why the mix is preferred for sheetmetal.
Hope that helps. I didn't ask about the regulator...that may have been an unfortunate coincidence I'm thinking.
 
Last edited:
That does help, thanks.

I have another set of gauges I’m going to swap in to see if the problem persists.
 
Righty Tighty said:
Okay, thanks for your input. I’m leaning towards a bad gauge and/or regulator. I’ve read that CO2 can damage (from the cold temperature) your gauge if the gauge isn’t meant for CO2, but this is a CO2/Argon gauge.
Click to expand...
There should not be appreciable "cold." There is normally not enough flow to cause that. IF it is frosting up, getting really cold, it might be you have a leak in the system somewhere, causing more flow. It might also be that you have more flow than needed, causing cooling/ frosting. I don't normally use one, except for checking, you might pick up an inexpensive flow gauge. You may be aware, they make them that you just hold on the end of the gun, and measure that way. You can then use the pressure for a reference, assuming the regulator is working correctly.

Like one of these:

ShieldingGasFlowTestGaugeforTIG_MIG_Plasma.png
 
Okay, just got back from the welding supply shop. Turns out I was using the wrong regulator. Even though the gauges are compatible with CO2, my regulator was not. I picked up a regulator specifically for CO2 and the welds look vastly better. Not even very much spatter.

Thanks for all the input, as always.
 
Amazing. I thought all migs were likely CO2 compatible, after the mix gas is largely CO2. Mine came with an adapter that screws onto the regulator to adapt from the mixed to the CO2 tank
 
What you say makes sense.

I had been using the adapter for my other gauges that failed, this set of gauges didn't need the adapter -- had the correct fitting for CO2. Maybe I got taken for a ride and it's my old gauges that failed? I'll try them on another machine using 75/25 and see what happens.
 
I’ve never heard of needing a different regulator with different inert gas's
When the working pressure you set keeps going higher, the diaphragm inside the regulator is bad
 
Man, I want my eighty bucks back! Maybe the guy who sold it to me didn't know what he was talking about.

I'm going to try the old regulator with 75/25 again and see what happens.
 
Uh--oh........

Regulators can develop weird troubles. I've taken them apart, and can't see anything that should be wrong. But they can get "sticky" and unstable
 
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