new old stock gas mixer questions
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  1. #1
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    Default new old stock gas mixer questions

    I picked up this gas mixer. The guy who sold it to me said he used to work at Airgas and back in the day they sold tons of these. He had one he kept when he left the company and said he had never used it.

    It has no controls at all. The box is riveted together - clearly they don't want guys like me to open it up and see the contents. It's shaped like a tall narrow shoe box. At one end are three gas hose connections. They are labeled Ar, He, and CO2. At the other end of the box is a gas outlet. Here's a picture:



    The way it's supposed to work is you have 3 hoses coming from 3 cylinders (argon, helium and carbon dioxide). On the cylinders are not flowmeters. Rather, they are regulators each set to exactly 30 psi. Depending on which hose you attach to which mixer input, the output will be different gas mixes. Here is the hose connection diagram:

    http://www.nwnative.us/Grant/images/...ngeDiagram.pdf

    OK so far? Here's the first question: how can I indelibly and permanently label the hose ends so I don't get them mixed up? (no pun intended)

    Second question: have you ever seen or heard of a mixer like this? I can find no information on the Web, and I like to think I'm reasonably good at searching. It was manufactured by Viri Manufacturing in Fairfield, California. The model name is PGM-1 (probably portable gas mixer?). Failing that, do you have any idea how this is designed to work?

    Next question: what if I went outside their guidelines? For example, what if I hooked a properly regulated oxygen supply to the input labeled CO2? Would I get something like 98% Ar + 2% O2?

    One of their pre-programmed mixes is C12 i.e. 88% Ar + 12% CO2. Would this work OK in place of C25?

    I have not yet been able to try it out. I have 3 regulators but I have to rebuild 2 of them, so I'm waiting for parts to arrive in the mail.

    My goal is to be able to weld in spray mode with my MM252, also to be able to get rid of my cylinders of trimix and maybe even of C25.

    metalmagpie

  2. #2
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  3. #3
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    OK, you guys are off the hook. I think I've figured out answers to all my questions just by reading the patent. Works a lot better if you download the document, LOL.

    metalmagpie

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    So there is a "tee" fitting in the sheet metal box ?

  5. #5
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    Sort of. There is a mixing body with 3 inlets (each with check valve). Each of those inlets has an adjustable jet arrangement, to vary the flow. The jets were carefully calibrated at the factory to accurately yield precise gas blends. The blends called out on the page above are only accurate if each input gas is at 30 psig. So if I didn't want C12, for example, I could turn down the pressure on the CO2 regulator a bit and the result would be more like C10.

    metalmagpie

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