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Mixing gases on the fly

General welding questions that dont fit in TIG, MIG, Stick, or Certification etc.

Mixing gases on the fly

Postby RoatanBill » Sun Jul 09, 2017 11:22 pm

If I have a cylinder of Argon and a cylinder of CO2 can I use the flow meters to mix them for MIG? e.g. 9 Ar + 1 CO2 = 10 mixed gas.

If I drill completely through a 1" block of metal then drill another hole perpendicular to the first but stop as soon as I hit the other hole, I form a T inside the block. On the leg of the T I put the output hose. On the remaining openings I connect the cylinders. The gases will be pointing at each other for mixing and then go out the exit to the welder. Would this work?
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Mixing gases on the fly

Postby Coldman » Mon Jul 10, 2017 8:24 am

It might work as long as you have regulators on cylinders which will prevent back flow. You might consider another downstream mixing chamber like a capped piece of 3" pipe before sending the mix to the torch. This will break up any stratification that might be going on or maybe fit a swirl to the mix tube.


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Re: Mixing gases on the fly

Postby RoatanBill » Mon Jul 10, 2017 10:15 am

I wondered about back flow. I have no idea if these regulators have back flow prevention, but common sense tells me they wouldn't. They are expecting flow only in one direction, so why engineer another 99.99999% useless valve into the device.

I suppose I could get some electronic valves and tap into the signal line of the welder to trigger them. It would then take 3 valves for flow to happen. Cumbersome but doable.

The main question still is would my idea actually work. Would the flow meters produce their gas streams in the ratios I'm expecting using my simple example? Would the 9 flow from the Argon cylinder overpower the 1 flow of CO2? I have to believe the need to mix gases as I've described - on the fly - has come up before. I'm wondering if anyone has experimented with this.
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Re: Mixing gases on the fly

Postby cj737 » Mon Jul 10, 2017 10:40 am

easiest and more common to use a Y connection that's backflow prevention built-in
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Re: Mixing gases on the fly

Postby RoatanBill » Mon Jul 10, 2017 11:02 am

I didn't know such a thing as you mention existed.

Can you list a source for where I could purchase a Y with back flow prevention? If this exists, then it exists for a reason - namely to mix gases from two sources. I can't think of any other possible reason and therefore my idea must have merit. A description of the device would possibly tell me if I'm correct.
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Re: Mixing gases on the fly

Postby Poleframer » Mon Jul 10, 2017 11:04 am

Just Y them together. I use this setup all the time, works fine. Since the pressure from the regulators are so far below that of the tanks, I dont see how gas can back flow into a tank.
I use a valved Y after my argon flowmeter that I can choose to send argon straight to my tig, or turn that off and open the other valve to a Y to the hose from my Co2 flowmeter for mig. Or if I turn both off I have straight Co2.
I've been doing some spray transfer with my 8vs, and its a hoot. I just float the ball on the Co2 and run about 20-25 cfh argon.
There are several discussions on it on weldingweb. Irishfixit had a couple good ones.
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Re: Mixing gases on the fly

Postby RoatanBill » Mon Jul 10, 2017 11:13 am

Thanks for the mention for weldingweb.

What's an 8vs?
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Re: Mixing gases on the fly

Postby cj737 » Mon Jul 10, 2017 1:58 pm

It's a suitcase welder from Miller

http://store.cyberweld.com/weingasyco.html
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Re: Mixing gases on the fly

Postby olek » Tue Jul 11, 2017 5:28 pm

Poleframer wrote:Just Y them together. I use this setup all the time, works fine. Since the pressure from the regulators are so far below that of the tanks, I dont see how gas can back flow into a tank.
I use a valved Y after my argon flowmeter that I can choose to send argon straight to my tig, or turn that off and open the other valve to a Y to the hose from my Co2 flowmeter for mig. Or if I turn both off I have straight Co2.
I've been doing some spray transfer with my 8vs, and its a hoot. I just float the ball on the Co2 and run about 20-25 cfh argon.
There are several discussions on it on weldingweb. Irishfixit had a couple good ones.


That is good to read that you mix co2 and argon with success. I asked a similar question in France and was shown specific mixing equipment, very expensive, with I think a warmed chamber for the co2.

I need to look at the answers but I was told about specific problems when mixing directly from the bottles.
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Re: Mixing gases on the fly

Postby cj737 » Tue Jul 11, 2017 7:09 pm

olek wrote:I need to look at the answers but I was told about specific problems when mixing directly from the bottles.

I use a premixed bottle which has its own potential problems. If left too long, the different gases will separate (stratify) within the bottle and change the gas mix coming out of the Regulator. So, it's either expensive or shelf life issues.
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