[steve-l]

Are check valves required at each regulator. I assume the regulator itself acts as a check valve. Any other tips will be welcome as well. I have just ordered a bottle, but nothing else at the moment.

[Poland308]

Most regulators do not act as a check valve. You can do it with out check valves and get it to work but a dedicated mixing valve designed for the gasses you will be mixing will give you the best results with the least miss match on the mix ratio.

[Otto Nobedder]

Actually. I've done it without check valves... A regulator in good condition will not allow enough back-flow to have noticeable mixing through the life/use of the contents. Check valves are cheap insurance, though.

You do not need a "wye" fitting to mix the gasses, a tee will do just fine. The gasses mix very quickly from a tee due to the induced turbulence, and there's a lot of hose between this tee and your weld.

Your flowmeter/regulators should be matched in pressure, i.e. each set at 60 psi, so your mix is consistent at the start. (A second of pre-flow will completely stabilize it.)

Keep in mind, unless you have a helium-specific flowmeter, it's hard to read Helium under 10 CFH, so it's challenging to set a precise ratio.

Steve S

[echosixmike]

I just buy 75/25 He/Ar pre-mix. S/F....Ken M