Nitrox/Oxygen safe O-Rings??

[CPTOZZY]

I just had to take my Nitrox tank in to get filled, and replace an O-ring at the valve where the regulator attaches. I went with the more expensive Oxygen safe O-ring, but I was wondering if it really matters. I realize when filling Nitrox they will partially fill with 100% O2 then add air, but this O-ring is External to the tank, not to mention that the O-ring is touched with bare fingers when applied, so the potential is there for carbon-contamination.

What I'm wondering is if these Oxygen safe O-rings are used for safety reasons during filling, or are used because they will last longer when exposed to the higher PO2 of Nitrox?

Thanks

[awap]

With pure O2 you need to be using O2 compatible materials. With nitrox (>= 40% O2) O2 compatible o-rings will last longer.

[CPTOZZY]

Originally Posted by awap

With pure O2 you need to be using O2 compatible materials. With nitrox (>= 40% O2) O2 compatible o-rings will last longer.

When Blending the O2 they start with pure (100%) Oxygen, and then add air, so there is the potential for explosive combustion during the filling process, but I'm wondering if by touching the O-Ring with your fingers (which will always have some carbon /grease) you negate the "safety" afforded by the Nitrox safe O-rings.

As far as O-ring Longevity, this is for my regular tank (I usually fill it with 32%), It is not a Stage Bottle (>40%) .... and anyway I'm not certified to use EAN greater than 40%. Will there really be any appreciable longevity?

[awap]

Originally Posted by CPTOZZY

When Blending the O2 they start with pure (100%) Oxygen, and then add air, so there is the potential for explosive combustion during the filling process, but I'm wondering if by touching the O-Ring with your fingers (which will always have some carbon /grease) you negate the "safety" afforded by the Nitrox safe O-rings.

As far as O-ring Longevity, this is for my regular tank (I usually fill it with 32%), It is not a Stage Bottle (>40%) .... and anyway I'm not certified to use EAN greater than 40%. Will there really be any appreciable longevity?

Sorry, I had my alligator going the wrong way. I meant <= 40%.

None of my tanks are O2 cleaned and I only occasionally dive them with nitrox. I do my own servicing and usually stick with EPDM or Viton o-rings. But iw will occasionally use buna o-rings with no real concerns. I often use buna tank o-rings because they never are exposed to high O2 and they get changed fairly often. Besides being better with O2, EPDM and Viton have a number of other favorable properties for scuba applications.

[CPTOZZY]

Originally Posted by awap

Sorry, I had my alligator going the wrong way. I meant <= 40%.

None of my tanks are O2 cleaned and I only occasionally dive them with nitrox. I do my own servicing and usually stick with EPDM or Viton o-rings. But iw will occasionally use buna o-rings with no real concerns. I often use buna tank o-rings because they never are exposed to high O2 and they get changed fairly often. Besides being better with O2, EPDM and Viton have a number of other favorable properties for scuba applications.

The O-ring I got for my tank was Viton I believe. It was Brownish. I also got one of those scuba tank shaped O-Ring Holder Keychains, which came with several Black O-rings of various thickness.
What are Vitem, EPDM, and buna O-rings?
What do they look like?
What properties / Benefits vs risks does each one have vs. the other

Thanks