Where to buy an electrically controlled variable flow 3000 psi air valve

I would start with a co. like AirLiquide, or or Air Products. You are getttin up there in psi but not too, to bad. They don't make the valves but they do use similar in applications.

Whitey, Carten, Nupro are all reputable vale manufacturers. They don't make what you are looking for that I am aware of but it is a good starting point.

Contact http://www.proportionair.com/family_custom.asp.

Our host GlobalSpec would be a good starting place.

What you need is a Dome regulator similar to this www.cashco.com/techbulletins/da34.pdf .

Then source an magnetically controlled low pressure air regulator with auto bleed off with which to control the dome loader.

This can be controlled from analog, digital or manual inputs.

We'd be remiss not to mention for DIY'ers that working with pure oxygen is incredibly dangerous. Even a tiny metal shaving in the piping that goes bouncing down the line is enough to cause ignition. Similarly you want to be careful of the materials the Oxygen contacts to prevent rapid corrosion.

As with anything, don't do it unless you thoroughly understand what you're getting yourself (and those around you) into.

As guest mentioned: Danger. at high pressure, small orifice the friction of the escaping gas can cause ignition.

So again - caution, cuidado, etc, etc.!

Thanks all for your suggestions & input.

I am very aware of the dangers of oxygen - hence why I specified it in the original question - but it is good practice to let others know.

For info, the application is related to filling of SCUBA cylinders, specifically mixing of NITROX (enriched oxygen) fills. The process for doing this is to determine the current mix & pressure in the cylinder (they always have some pressure), decide the required mix when full (approx 240bar) first add the correct amount of O2, then top it up with filtered air - an O2 meter is then used to confirm the mix with the customer.

very well. in my short time here (CR4) I have seen some questions, or more accurately, series of, that make me VERY uneasy. Apparently some feel that the page can teach the pupil. We know this to not be true.

Blue waters,

Charles