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I am working with ozone produced with an ozone generator and pure oxygen.

The resulting O2 / O3 gas mixture is probably about 80-85% O2 and up to 15-20% O3.

The generator does produce about 500g of O3 per hour.

Currently I am using PTFE tubes to bring the O3 where it is needed.

However I am not happy with the mechanical properties of the PTFE tubes, as they are stiff and as a result they are uneasy to work with.

I have found now that EPDM tubes are way easier to work with, but I have doubts about their resistance to O3.

While many datasheets and Wikipedia do tell that EPDM is resistant to O3, I question if it is really resistant to extreme high concentrations of O3 on the long run.

Switching from PTFE to EPDM in the future would be a good thing as EPDM is also cheaper and easier to work with.

Does anyone here have experience with high concentrated O3 and EPDM?

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The problem with EPDM is that it has tertiary carbon sites (and some double bonds for cross-linking). Forget the latter as let's assume the material is already cross-linking. Normally carbon backbone polymers with substitution need anti-oxidants to prevent the C-H, where there is a side group, from oxidising. These delay the oxidation process and define the lifespan of the material. So after time, the anti-oxidants will be consumed and the polymer will be prone to oxidation, which leads to fragmentation. Ozone is a great oxidant as you know. When we used high pressure ozone, we always used fluorinated everything. By using fluorine saturated polymers, there's no sites for oxidation to occur.

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The remaining double bonds from the (usually unconjugated) diene compound are not in the backbone, because otherwise the name would be EPDR, R for rubber (which is not a common material afaik).

That makes it resistant to oxonolysis, which cuts the backbone of butadiene or isoprene based rubbers, especially under mechanical load, because the latter exposes more and more new double bonds to the attack. This is what makes the well known cracks on the sides of older tyres.

Also EPDM products are always vulcanised, or otherwise crosslinked, so your tubing does not contain any significant amount of double bonds that could get ozonolysed.

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