Question about o-ring codes and measurements

[WhiteSands]

I can find dimension charts for o-rings that are of the description "AS568-XX" where XX is a 2-3 digit number.

However there are some o-rings labeled S-8-N85 in my service kit. What is the difference between this and the AS568 o-rings and where can I find dimension charts for these?

Secondly, in my regulator parts manual, it lists "N" numbers after the o-ring description numbers. E.g. Viton o-ring AS568-112 N85.
What does this N85 mean? Some are N85, some are N70.

Thanks!

 

[kwinter]

I'm pretty sure the N85 and N70 are the durometer (hardness) measurement. Low pressure uses a slightly softer 70 or 75 duro o-ring while HP needs a harder 85 or 90 duro.

 

[captain]

I believe th N signifies nitrile(buna N) and the number is durometer hardness.

All you want to know about O rings

O-Ring Specialists, Viton® O-Rings, Kalrez® O-Rings, Buna O-Rings, O-Ring Design and Material Selection Guide, Buy O-Rings Online

 

[kwinter]

I agree with you Captain, but the OP clearly listed something as "Viton o-ring AS568-112 N85". It can't be both Viton and nitrile. I get mine from oringsusa.com and they are labeled V75 and V90. I haven't used a Buna ring in years.

 

[diversteve]

I think it means the manual writer didn't know what they were talking about...

just a guess.

 

[WhiteSands]

Thanks for the tip, so the "N" number denotes hardness.

Anyone has a clue about where to find a sizing chart for a "S-8-N85" o-ring?

 

[deeper thoughts]

I believe th N signifies nitrile(buna N) and the number is durometer hardness.

All you want to know about O rings

O-Ring Specialists, Viton® O-Rings, Kalrez® O-Rings, Buna O-Rings, O-Ring Design and Material Selection Guide, Buy O-Rings Online

Thnx for the link

 

[redacted]

Thanks for the tip, so the "N" number denotes hardness.

Do you have a reading comprehension problem?

 

[WhiteSands]

Do you have a reading comprehension problem?

Which part have I misunderstood?

I'm pretty sure the N85 and N70 are the durometer (hardness) measurement. Low pressure uses a slightly softer 70 or 75 duro o-ring while HP needs a harder 85 or 90 duro.

I believe th N signifies nitrile(buna N) and the number is durometer hardness.

You have a nice day too.

 

[ams511]

The N85 could be a custom specification. If you order large amounts of o-rings (say your Scubapro) you can get them custom made to your exact specs. You are not going to easily find a viton duro 85 o-ring, I would substitute it with a duro 90 if it is going to see high pressure.

The AS568 is only one spec. There are other specs such as metric o-rings, a British spec, and mil specs. You may need to measure the o-ring to find a replacement. Alternatively, if the o-ring is neither cut nor distorted you could re-use it, especially if it is for a static application.