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  • CO2 generator

    Does anybody have plans for a CO2 generator that uses either propane or natural gas to generate mig shielding gas? A quick look online shows they are extremely popular for growing indoor crops. Not what I want or need.
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  • #2
    Evan, why not use the propane as your shielding gas, you'd certainly get CO2.
    And water and soot.
    West Sussex UK

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    • #3
      Originally posted by Evan
      Does anybody have plans for a CO2 generator that uses either propane or natural gas to generate mig shielding gas? A quick look online shows they are extremely popular for growing indoor crops. Not what I want or need.
      Originally posted by Evan
      That's right. My wife is in the compressed industrial gas business and sells bottles, not rents them. The actual cost of gases is almost nothing. Most acetylene is made from natural gas and 1000 cubic feet of natural gas was $6.31 on Friday and will make around 300 cubic feet of acetylene as well as CO2 and a bit of helium while providing all the energy needed to run the process. If you assign all the raw material and energy cost to the acetylene then the cost of production, not counting plant amortization, is 2 cents per cubic foot.
      why do you need it ..you must get it cheap ..

      what about doing some more in-depth study ..on car exhaust gas . lpg car exhaust gas


      and another thing ..i thought your MRS was big in grinding wheels ..

      all the best.markj
      Last edited by aboard_epsilon; 07-02-2009, 11:24 AM.

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      • #4
        Originally posted by Evan
        Does anybody have plans for a CO2 generator that uses either propane or natural gas to generate mig shielding gas? A quick look online shows they are extremely popular for growing indoor crops. Not what I want or need.
        I've been kicking this very thing around for several weeks. I have concluded it is possible to trap the exhaust gas from a torch and to cool and dehumidify it, and then store it in a low-pressure or even high pressure container. The last step is to see what the welds look like. I was thinking there could be a good HSM article in it if it works well.

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        • #5
          I get absolutely no breaks on the gas refills. She is a dealer for a larger company and they don't give discounts to anybody.
          Free software for calculating bolt circles and similar: Click Here

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          • #6
            We had a long thread about DIY CO2 generation (for welding) several months back.

            Straight CO2 gives a lousy arc compared with C25. It's hot, fiery arc that creates a ton of spatter. Straight C02 also oxidizes a lot more than C25, so most welding texts warn against using it on aluminum or stainless steel.

            I've used straight C02 on structural steel, and it was miserable. It penetrates like crazy though! Never tried it on aluminum.
            "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

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            • #7
              So, how's Cap & Trade going to work with that?
              Jim H.

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              • #8
                Originally posted by JCHannum
                So, how's Cap & Trade going to work with that?
                I don't think anyone has any expectations that Cap and Trade is going to work regarding CO2 levels - it is only supposed to generate tax revenue and limit growth. That, I think, it is where it is going to do very well.

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                • #9
                  I figure a propane tank would make a good storage vessel. I'm not sure how important it will be to dry the gas. CO2 breaks down in the arc to carbon and oxygen anyway and water would do the same except for adding some hydrogen. Not sure in what direction the reactions would proceed but in theory you could synthesize nearly any simple hydrocarbon.
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                  • #10
                    Originally posted by lazlo
                    We had a long thread about DIY CO2 generation (for welding) several months back.

                    Straight CO2 gives a lousy arc compared with C25. It's hot, fiery arc that creates a ton of spatter. Straight C02 also oxidizes a lot more than C25, so most welding texts warn against using it on aluminum or stainless steel.

                    I've used straight C02 on structural steel, and it was miserable. It penetrates like crazy though! Never tried it on aluminum.
                    I'm pretty sure the gas mix contained in propane exhaust is far from pure CO2 - but what it is isn't exactly clear. Certainly it will have a lot of what air is made of but with higher levels of CO2 and far less oxygen.

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                    • #11
                      Originally posted by Evan
                      I figure a propane tank would make a good storage vessel. I'm not sure how important it will be to dry the gas.
                      Removing water is just a good way to help the storage tank last longer.

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                      • #12
                        Originally posted by dp
                        I'm pretty sure the gas mix contained in propane exhaust is far from pure CO2 - but what it is isn't exactly clear. Certainly it will have a lot of what air is made of but with higher levels of CO2 and far less oxygen.
                        The problem is that you need an inert shielding gas for TIG and MIG. So C25, which most people use for MIG, is 75% Argon with 25% C02 added to enhance penetration on steel.

                        For MIG'ing Aluminum, most people use pure argon, because of the oxidation issues I mentioned.
                        "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

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                        • #13
                          Aside from traces of odorants and other LPG molecules the exhaust will be Nitrogen, CO2, virtually no free oxygen and NOx. How much NOX depends on the combustion temperature of the generator flame but to maximize clean gas output you would want a stoichiometric mixture. The largest monomolecular component will be the nitrogen and it will have a small nitriding effect on the weld.

                          [edit]It certainly won't be the same as using straight CO2.
                          Last edited by Evan; 07-02-2009, 11:54 AM.
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                          • #14
                            Evan,does your machine use an adjustable flow meter,or is it the fixed rate kind that comes with the machine?

                            Reason I ask is the fixed variety are set to a happy medium,but actually waste gas indoors.Having an actual flow meter can save you a third of a bottle welding indoors.
                            I just need one more tool,just one!

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                            • #15
                              It's a fully adjustable two stage regulator/flowmeter.
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