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Can I use UHP gases?

If you want to use ultra high purity (UHP) gases it is important to evaluate the gas line and mixer and where and for what it will be used.

Many people would buy UHP gases but waste the money as the gas line or experimental setup anyway cannot keep impurity levels that low. Or they have UHP gases, but don't know how to change bottle correctly, and thereby lose purity even before the gas line.

If you have UHP gases, you can of course supply them to the ProGasMix (and ProboStat) but they will increase the levels of impurities:

The ProboStat and similar high temperature equipment with ceramic walls at high temperatures, O-ring seals, and large surfaces will in our experience typically contain minimum 30 ppm of H2O and 10 ppm of O2. This comes from indiffusion, leaks, and desorption. By special means you can decrease them, probably to 1-10 ppm levels.

The ProGasMix is a smaller problem. If you use it properly and know how to flush gases etc. it should not contribute more than 1 ppm levels of impurities from outside.

But since the inside of the tubes is copper, there will be a bigger tendency of one gas - e.g. H2O or O2 from a wet oxidizing mix - to remain desorbing from the wall into the next mix, e.g. dry inert gas.

A steel tube mixer with steel flowmeters etc. would do this better, but if this is important, one should probably go for a simpler mixer, which cannot do so many gases and things as the ProGasMix, but is more designed UHP of one gas mixture at the time.

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