Be gentle on me. First post here. Over on rec.crafts.metalworking I asked about a device to mix gas from my argon and CO2 bottles for MIG welding. I got two suggestions, one was go to Ernie L's web site - should be there. It may be, Ernie only has about 10,000 links. I couldn't find anything.
Second suggestion was ask on this NG. Apparently you can build your own gas mixer with not too much difficulty.
Karl
I have such a device which I have yet to use. You hook up the two tanks both with regulators set to 50 pounds and set both of the dials to the same number. I had in mind to use it for argon and helium but it is clearly designed for those two gasses you mention. It is about the size of a toaster oven. I had to buy a whole bunch of stuff to get it as it wasn't lotted by itself but got about half of my money back dealing some of the other stuff off. I think it is called a proportional mixer.
I suppose you aren't supposed to do high pressure transfer between tanks but that is how I made my mix last time. Put 500 pounds of gas a in then bring it up to 1000 by adding gas b. do the co2 first as those aren't as high pressure
Fran
Ernie cobbled. His mixer uses two oxygen check valves made by Western Enterprises. Start with two flowmeters and two cylinders. Each flowmeter has a hose which goes to a check valve which goes to a Y fitting. The output of the Y fitting goes to the work. Specific fittings depend on your flowmeters.
Assuming you want 20 cfh of mixed shielding gas, use
15 cfh Ar + 5 cfh CO2 to get C25 (75% Ar, 25% CO2) 16 cfh Ar + 4 cfh CO2 to get C20 (80% Ar, 20% CO2) 18 cfh Ar + 2 cfh CO2 to get C10 (90% Ar, 10% CO2)... you get the idea
Grant
I thought that Ernie had something on his web site. He has everything else.
Search for TIG Gas de-mystified in this newsgroup. It is a thread on mixing gases.
Dan
I believe you can use two normal regulator / flow meter setups connected together with a Y or T. Just have to ensure that the regulator output pressures are matched to get a decent blend. What you have sounds like a higher precision setup, but I believe it's not needed for "normal" welding.
That last bit is called "partial pressure gas blending" and is very common in the SCUBA world for nitrox and other diving gas blends.
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