Gas Mixture

[GARAGEGADGETS]

I have a bottle of mixed gas that is 75% Argon/25% CO2, and was wondering if there is a way to check the actual percentages? I recently purchased a gas mixer and I would like to check the calibration of it by checking its mixing percentages. Can anyone help me.

[Mike W]

I know it can be done but the equipment would be expensive. What kind of a mixer did you get?

[GARAGEGADGETS]

It is a Smith standard two gas mixer 180 scfh argon /co2. I bought it used and was wondering how accurate it is. There should be a way to check the percentage of gas being mixed since each is a different density.

[Mike W]

I would like to have one of those. I am building one, just using flow meters to set the percentages of each gas. I would just use it and not be too concerned about just how accurate it is. I want to see if 50/50 is any different then 75/25.

[GARAGEGADGETS]

Mike, I opened the mixer's case and look inside, not much. There is a small mixing chamber and two metering valves one for gas mixture and the other is your flow rate. Smith requires a minimum of 55 psi on both gases for it to work properly. So I also had to buy Inert pressure regulators because my flowmeters would not go high enough. I am also looking into building a manifold that would allow me to feed a regulator and a flowmeter off the same bottle at one time.

[Mike W]

I have a flow meter that had a bad diaphram. I blocked it off and am just using the flow meter part of it on the output of the mixer. The funny thing is that if I set the flow meter on one of the tanks to say 20 cfh, the other flow meter will read higher. I expected it to read lower because it wouldn't have the correct pressure. There has to be a simple explanation but I haven't found it yet.

[GARAGEGADGETS]

Mike, it appears that on the mixer I have they use a fix orifice to control the flow of Argon ( no adjustment ) that is why they require a minimum pressure on both of your input gases but you a can control the amount of CO2 you are mixing by adjusting the metering valve which then passes into the flowmeter.

[Mike W]

Thanks for the info. This mixing stuff is kind of interesting. I will post some pics once I am convinced I know what I am doing.