CO2 or C25?

Next time look for leaks when you first hook up your cylinder.

There aren't too many CO2 cylinders around, just the little ones. At your usage rate (11 pounds of wire a year) you might get away with a little cylinder, but lots of us burn about 8 times that amount and don't want to be running to the welding supply all the time. Plus, if you pull much CO2 out of a cylinder it will freeze up the regulator, requiring one of those heated regulators. Again, not applicable in your case due to low volume.

I picked up a large CO2 cylinder recently, paid $35 for it (full) and figured I'd give it a try. Then just for grins I threw it on CL for $150. Some guy with teenagers who were way into paintball bought it instantly. Shrug.

Grant

The leak was internal at the solinoid. Took some digging to find it. I noticed my flow meter (gauge type) was dancing a smidge right off the zero mark with the welder not running. My hearing is so bad I never could hear it..but then..I cant hear most leaks unless they are huge.

Ive welded aprox 15' of welds in less than 10 minutes, with no freezing noted, even in winter. I mistyped btw..that should have been

33lbs per year. Im not home all that much...shrug.

It will be intersting to see others responses.

Gunner

CO2 does work for steel heavier than 1/8", but on sheet metal I found it difficult to not burn holes. C25 will cover a wider range, from 18 ga sheet to spray mode on heavy plate.

When I started at South Seattle we still ran CO2 for some heavy MIG, but after a few years we went all C25. We did that because industry has pretty much abandoned CO2. While a lone welder working on his own projects can afford to remove a bit of spatter, but not having to remove spatter saves production welders a LOT of time.

True indeed. Its MUCH hotter than C25. Which is nice on rusty nasty metal. No more spare tire carriers going AWOL...(blush)

Good answer and good reason.

With most of the rough welding I do, a bit of splatter isnt an issue, and spraying the work piece with Pam or antisplatter spray works pretty well. Hitting the area with a knotted cup brush usually takes any splatter off anyways.

I do have 5 tanks of C25..but hate to spend the money filling them so often for rough work.

I still stick weld a great deal, and cleanup on that is far far more problematic than the tiny amount of splatter from CO2 welding.

So for the sort of work stick welding would be used for..then CO2 makes sense?

Gunner

It seems to me that mixed gasses with CO2 would allow much less total gas in a tank because only the CO2 liquifies, and that cost would probably be a lot higher for that reason. Is that true?

CO2 is still a lot cheaper so if the work fits use it.

CO2 is shipped as a liquid so the tanks last a LOT longer. C25 is simply a compressed gas mix with no liquid.

After this next time, I'm going to swap my owner bottle of mixed gas for an acetylene, and buy a CO2 for MIG. I need an acetylene, and this will allow me to do this with less outlay.

STeve

The CO2 in the tank doesn't liquify due to the pressure?

Yes - it goes into a solid also. Martin

Mart>>> It seems to me that mixed gasses with CO2 would allow much less total gas in >>> a

It has to do with how it is processed. From what I have heard from gas suppliers the CO2 does not liquify when mixed with Argon.

Another one of those little mysteries.

It seems to me that if it liquified it would remain a liquid until the bottle pressure dropped below its vapor pressure. So you would get only argon in the beginning.

Don Young

Ernie, off topic for a moment... I sent you a question about hard surfacing an anvil via email at your website. I hadn't gotten a response so I'm wondering if you received it?

(It's not an anvil, actually... more like a Chinese "anvil-shaped-object"! har har)

Must have gotten killed by the spam filter.

You can hard-face a cast iron door stop, but you have to lay down a "buttering pass" of something else for the hard-face to stick to.

The most likely candidate is a nickel based cast iron welding rod or wire.

If you lay down a full layer of nickel then you can lay down a few layers of hard-face.

The best process would be to lay down Nickel, then a layer of mild steel, then at least 2 layers of hard-face.

I believe it forms an azeotrope with a BP 0f -185 C

See

Tom

Thanks Ernie. It's a small little 24 lb. cast iron "door stop" so I won't invest the nickel and hard-facing material into this piece. I'll find some steel plate and build my own anvil following your example on the website.

Michael

Not a great mystery, just some basic chemistry - you remember, the fun stuff :-). A gas will liquefy when its partial pressure exceeds its vapor pressure, so long as the temp is under the critical temp (about

105F for CO2). For CO2 the vapor pressure at room temp is about 550-650 psi, the gauge pressure you are used to seeing on your CO2 tanks (varies with just how hot your room is :-)). For C25, if the total tank pressure is 2000 psi the argon partial pressure is 1500 psi and the CO2 partial pressure is 500 psi, which is just low enough to prevent liquid from condensing. Hmm, on a cold winter day, I wonder if some does condense and mess up the mixture? Anyway, since liquid is roughly 100x denser than gas (depending on pressure, of course), that "little" tank of liquid CO2 will way outlast a tank of C25 gas.

-- Regards, Carl Ijames carl dott ijames aat verizon dott net (remove nospm or make the obvious changes before replying)