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  • #16
    My 20# CO2 tank costs me less than $20 to refill.

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    • #17
      Originally posted by kvom
      My 20# CO2 tank costs me less than $20 to refill.
      Imagine how far that $20 would go if burning propane was an effective alternate. Or natural gas. Especially if that natural gas was also used to heat your shop.

      You'd have fuel enough to power your new government mandated green lawn mower, your new efficient Government Motors Chevy, and a couple miles of bead.

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      • #18
        I suspect you'll be using that "miles of bead" to repair your Government Motors truck and your Green Mandate lawnmower.
        This product has been determined by the state of California to cause permanent irreversible death. This statement may or may not be recognized as valid by all states.
        Heirs of an old war/that's what we've become Inheriting troubles I'm mentally numb
        Plastic Operators Dot Com

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        • #19
          I'll enter a comment on this. There are commercial devices that are used to generate furnace atmospheres by partially combusting natural gas with heat and a catalyst. Depending on the degree of combustion they are referred to as endothermic or exothermic gasses. Endothermic (heat going in) gasses are mostly CO and methane, with some CO2 and hydrogen. Water vapor, of course. Exothermic (generating heat) gasses have a lot more CO2, less CO, almost no methane or hydrogen and a lot more water vapor. An exothermic reactor that burns propane would be an effective CO2 generator, I would think. A big project, but Evan isn't one to avoid that sort of thing. As an aside, I have a tale of an endothermic generator in South Boston. In 1979 I was working for Airco, and with natural gas prices at record highs Airco was selling a furnace atmosphere system that was intended to replace cracked natural gas atmospheres. We went to a sintering plant in Southie and as part of the preparation for conversion we analyzed the gas they were using. These gas generators are typically set up by checking the dew point of the product gas, given that natural gas is very dry, and any water vapor comes from the catalytic reaction. We found that their gas dew point was very high, but a gas chromatograph showed that the other gas constituents were in the proper proportions. WTF?! Having run out of ideas we checked the dew point of the natural gas and found it was quite wet. A call to the gas company and the shocking truth is revealed. The gas mains in that part of town were put in when the gas was manufactured by cooking coal at the gas works, and were made of wood. The manufactured gas had plenty of water vapor, and things were OK until natural gas took over and the mains dried out, cracked and leaked. In addition, dust in the mains got kicked up and clogged jets, etc. Rather than replace the mains the gas company just raised the dew point, 99% of users didn't care and the others adjusted in other ways.

          Joe

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          • #20
            I happen to have one item that should make it a reasonably easy job to build a gas generator. Sitting in the garage shop is a brand new catalytic converter that I removed immediately from my Ford Ranger when I bought it new in '88. All it should take is a small pilot burner to get the temperature up to operating condition and then I will have two things. Clean combustion gas and shop heat. Another idea occured to me and that is using the burner from a pulse combustion gas furnace. The only problem with that is I don't have one but it should be close to ideal. The exhaust gas from those can be vented with plastic pipe they are so efficient.

            I am going to experiment with this in the near future so I will be reporting on what I find. I don't think it would make a publishable article as there are too many potential liability issues, at least in the US.
            Free software for calculating bolt circles and similar: Click Here

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            • #21
              I remember seeing a video either on youtube or DIY about a guy doing this but I can't remember how he generated the CO2

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              • #22
                Originally posted by deltaenterprizes
                I remember seeing a video either on youtube or DIY about a guy doing this but I can't remember how he generated the CO2
                from homebrew ..catching it in bin liners then compressing it , and putting it in an LPG bottle.

                OK if you are a boozer and have weeks to wait .

                jusat had to get a bottle ..i use one bottle a year and it costs me over £100

                all the best.markj
                Last edited by aboard_epsilon; 07-02-2009, 03:32 PM.

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                • #23
                  Originally posted by kvom
                  My 20# CO2 tank costs me less than $20 to refill.

                  Right. It's very economical. Contrary to the views of some folks, CO2 for mild steel MIG works very nicely for me. Penetration is excellent and, if the tip is kept clean and used with liberal quantities of welding gel, spatter is negligible. I pay $23.00 for a refill on a 20# cylinder that I own.

                  That's equivalent to 160 cu.ft of Argon or C25 which is closer to $70 out the door. It's an easy decision for me.

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                  • #24
                    I'm not trying to change the subject too much, but for around the home shop, why not use one of the flux core brands like Innershield ?

                    I use it in My little sp125 and get good results. I also use it at work in a larger version for allmost all of our structural steel requirements . I have not had a weld inspection fail yet(knock on wood) and You don't have to wory about running out of gas after the store closes either.

                    Steve

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                    • #25
                      I do use flux core. It spatters and you use twice as much wire that costs twice as much money to do the same amount of welding. It doesn't make as nice a weld and the flux must be completely removed before painting. Other than that it's fine.
                      Free software for calculating bolt circles and similar: Click Here

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                      • #26
                        i'm just wondering, now that CO2 is considered a toxin in the US, would a CO2 generator be classified the same as a mercury generator or a dioxin generator? i wonder if i'll need a hazardous materials transport permit to take my CO2 bottle to be refilled.

                        andy b.
                        The danger is not that computers will come to think like men - but that men will come to think like computers. - some guy on another forum not dedicated to machining

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                        • #27
                          Evan those are exactly the reasons I don't use co2 anymore.
                          I find a lot of wire wasted on spatter and more time wasted on cleanup.
                          I realized the 75% argon 25% co2 blend isn't cheap, but then neither is my time nor the item I'm welding at any given time.

                          If I'm really after penetration that a 250amp mig won't do I'll reach for the stick.

                          I think if you do a feasibility study you'll be time and money ahead by just biting the bullet and do what everyone else in the industry has, and go with the 75/25.
                          I respect your inclination to travel the road less traveled, but sometimes it can be the long way home.
                          Home, down in the valley behind the Red Angus
                          Bad Decisions Make Good Stories‚Äč

                          Location: British Columbia

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                          • #28
                            Flux core also produces a LOT of smoke.

                            There's a time and place for it, as there are various FC electrodes that create alloys due to the elements contained within the flux, but there's a trade off of post weld cleaning that comes with it.

                            Having used FC indoors - I can honestly say you'd never catch me doing it at my shop ever again. The dust on everything is too much.

                            Co2 shouldn't cost more than about 15 bucks for a 10# bottle fill. Don't buy it at the LWS, buy it from a dry ice manufacturer. There's a huge market for dry ice in the medical field, and liquid co2 in pop dispensers, so find an outfit that services them to get your co2.

                            Argon/co2 blends are nice. For the occasional user, the cost increase is part of the cheapest consumables in the process. Even when I tig, I don't think too much about the gas consumption - it's simply not all that relevant. Your arc time per hour is so low in manual processes, that you'd have to go to great lengths to determine how much gas you actually used. 80cf of C25 in MIG will easily last through 20# of wire. How many home shop weldor's is burning through a roll every month? So even if you were, and you were doing it every month and you were paying $40 a fill - you're talking about spending $240 a year on gas. How many of you do work for less than 50 bucks? 5 jobs and your whole year's gas consumption is paid for.

                            The electricity used is probably more expensive than the shielding gasses. There again, your arc time is typically really low.

                            I typically get a full 44# spool out of a 125cf tank. That's a lot of weld for my $32 investment in C25 shielding gas.

                            The last bit of advice is get the biggest tank that makes sense for you. Shielding gas doesn't go bad. Having a couple hundred invested in a giant bottle might make more sense than spending that much every few months in service fees for the refills. Most of what the LWS is charging you is labor on the transaction. The gasses are pretty cheap, but they have to pay the monkey in the back room 20/hr or more to handle your bottle.

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                            • #29
                              You blokes in the states who can own your own bottles do alright, we have to rent ours, at 150 aud for an E size (don't know so don't ask, but the next size down from the big ones here) and about 80 AUD for a refill for CO2 I am paying out 600 AUD a year for the four bottles I have plus the gas I use, some years I use next to none, others several bottles of each.
                              Will

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                              • #30
                                Speaking from a position of moderate ignorance here, I weld TIG only with 100% argon (which is NOT cheap here)

                                I just wonder what the intense UV would do to the kind of reaction at the torch head that Evan suggests?

                                My only interest in CO2 is carbonating the soda for my whisky.
                                Believe it or not, it is cheaper for me to keep a bottle of CO2 for carbonation, than to buy bottled soda water at the supermarket.
                                Just got my head together
                                now my body's falling apart

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