[getherdone]

Gday,

hoping someone more experienced can explain this one. Gas is rather pricey where I am - with only one supplier for 75/25. Try $85 for 80 cubic foot bottle.

So I've been looking into C02 as an alternative as I run mostly Lincoln Outershield ('Dual Shield' flux core) wire rated for either gas.

My options are 20 pound C02 cylinder for $50, or 50 pound for $105, and no cylinder rental charge - I like that part too. From what I've read online 20#s C02 @ 8.74 cubic ft of gas per pound = 175 cu ft.

Can that be right?? The 20# tank is only 2' tall 7.5" diameter - while my 80 cubic foot 75/25 tank is 3' tall, 6.5" diameter.

Is there really more than double the c3/welding time as it turns to gas? I'm generally running between 25-30 cubic feet per hour as welding outside, often with a light breeze.

Hope I haven't missed something as just ordered a C02 specific valve from HTP today....


Thanks in advance.

D

[Poland308]

Not all gasses are the same density and compression of some gasses causes then to change state into a liquid at average temps. Do to that I believe that most co2 tanks will contain liquid. This allows you to get more cf of gas into the bottle. At an equivalent pressure argon is still a gas therefore you are limited to how many cf will fit in the bottle.

[MinnesotaDave]

My options are 20 pound cylinder for $50, or 50 pound for $105, and no cylinder rental charge - I like that part too. From what I've read online 20#s C02 @ 8.74 cubic ft of gas per pound = 175 cu ft.

Can that be right?? The 20# tank is only 2' tall 7.5" diameter - while my 80 cubic foot 75/25 tank is 3' tall, 6.5" diameter.

It is correct.
You buy 20 pounds of liquid co2 and it makes approximately 175 cu-ft of shielding gas.
I use it often because it's so cheap.

[getherdone]

Damn...ok.

I'm running .035 Lincoln Outershield and the suggested flow rates are the same for c02...

Before I do a happy dance mig torch in hand....am I really to expect DOUBLE the welding time for 20 pounds of C02 vs 80 cubic feet of 75/25?

D

[MinnesotaDave]

Damn...ok.

I'm running .035 Lincoln Outershield and the suggested flow rates are the same for c02...

Before I do a happy dance mig torch in hand....am I really to expect DOUBLE the welding time for 20 pounds of C02 vs 80 cubic feet of 75/25?

D

175 cubic feet of CO2 vs. 80 cubic feet of 75/25 and using the same flow rate...

I must be missing something because it seems pretty straightforward.

[getherdone]

Sounds simply too good to be true (for me)...so yes want to make sure I'm not missing anything:
• That's circa $23 for 80 cubic feet C02 vs the $85 I currently pay for 75/25
• The C02 bottle is noticeably smaller - yet holds more than double the volume as it turns to gas?!

No one on my home island uses C02 - hell the welding supply store didn't even know it was possible when I asked them about it, or why one would want to. Hence why I'm asking here...

The only available source I've found is from a Beverage distributor...so I guess I'll be finding out if food grade...is good enough for welding grade

D

[Keith_J]

Yes, argon is cryogenic and no amount of pressure will keep it liquid at our comfortable temperature range. Carbon dioxide has a critical tempetature of around 92°F with a critical pressure just over 1000 psi so it is easy to make a cylinder capable of twice that for safely handling super critical CO2. Cody's Lab on youtube has a video of supercritical CO2 in a glass tube..

You pay for the packaging which is why argon costs much more. Steel mills use liquid cryogenic argon, delivered in bulk. Your welding gas supplier most certainly has it delivered as a compressed gas. Same reason racing gas is $4/gallon at the track or $20/gallon in cans at a store.

[getherdone]

Fantastic, thank you gentleman.

Can't wait for that shiny new HTP C02 regulator to arrive

[MinnesotaDave]

Sounds simply too good to be true (for me)...so yes want to make sure I'm not missing anything:
• That's circa $23 for 80 cubic feet C02 vs the $85 I currently pay for 75/25
• The C02 bottle is noticeably smaller - yet holds more than double the volume as it turns to gas?!

No one on my home island uses C02 - hell the welding supply store didn't even know it was possible when I asked them about it, or why one would want to. Hence why I'm asking here...

The only available source I've found is from a Beverage distributor...so I guess I'll be finding out if food grade...is good enough for welding grade

D

20 years ago I used to bring my bottle to the local Pepsi bottling/distribution shop and they filled it for super cheap.

Now days I have to bring it to the local welding store and just swap it out.
Sometimes they give me an aluminum one with a pop company stamped on it, sometimes a steel tank.

You will experience a little more spatter build up on your tips, but I've not found it objectionable.
I do not use dual-shield though, only solid wire.

With solid wire it takes 1-2 more volts for proper operation, I'd guess dual-shield may be similar?

[getherdone]

Hi Dave...good story!

When I told Lincoln tech support I only had access to 75/25 they suggested using the same settings and simply dropping down 1 volt.

It does mean I will be maxing out my little Lincoln 210a machine however...she only goes to 25 volts.

D