Scubapro O-ring Sizes

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Is it possible to use Buna-N o-rings instead of EPDMs in tank valve?

Buna does not do well with O2. For an air tank I see no problem and use Buna 014s on all my air tanks and as save-a-dive spares so they may find their way onto a rental/dive op nitrox tank.

 

[V&G]

Thank you for this info. Does it mean I can always use EP o-rings?
Could I use them for inflator as well for valve?
When may I use NI, VT or PU o-rings?

 

[Zung]

Yes you can use EP always... if you can find them: the harder grade (Duro 90) for HP are hard to find. OTOH, VT (Viton) are easily ordered thru the Internet.

 

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I don't know of any scuba application where EPDM is inappropriate. But I have yet to find a ready source for EPDM in duro 90. I only use duro 90 in a couple HP applications. I prefer viton for rarely used o-rings since it has the best shelf life of the options. I still favor EU duro 90 for HP piston o-rings as it has the best dynamic characteristics and is most resistant to extrusion. In a pinch, I'll use buna in any application also; but I don't deal with high concentrations of O2 with any of my gear.

 

[V&G]

oringsusa.com has EP80 in stock, if you interested.

According to TSS found in this thread the o-rings used in inflators are Duro 85. Is it correct?
What Duro should be used for valve o-rings 014, 112 and 214?

 

[redacted]

oringsusa.com has EP80 in stock, if you interested.

According to TSS found in this thread the o-rings used in inflators are Duro 85. Is it correct?
What Duro should be used for valve o-rings 014, 112 and 214?

Thanks, I'm getting ready to resupply and EPDM looks good. I really dont worry much about =/- 5 duro.

I try to stay with duro 90 on those o-rings as they are all subject to extrusion. I have had a 214 extrude on a tank in my trunk. It was not as bad as I thought - just a steady hiss. Some din valves may take a 111.

 

[Zung]

oringsusa.com has EP80 in stock, if you interested.

Yes, but expensive: 10x EP70, 5x VT90. If you buy in bulk, you'll feel the pain. Viton is alright for now: I just stocked up on them.

 

[V&G]

Just discovered that there are a different shores for Durameter....


What shore we are talking about here?

 

[Zung]

Commonly, o-rings use "A" scale (Shore-A). "OO" is for softer material, and "D" is for harder.

 

[Couv]

Loosely, the Shore scale is related to the probe or “foot” used to measure the hardness of the material being tested. The foot is pressed onto the material being tested and the hardness is measured with a type of spring scale. If the foot used to do the measuring is too sharp, it will just penetrate the material and damage it giving an inaccurate reading. As Zung pointed out, Shore A is usually the scale used for o-rings, 00 for something softer, D for a harder material. The DIY method involves just comparing a known hardness o-ring to the one you need to “test.” Hold the o-ring between the thumb and forefinger and squeeze it closing up the hole; you’ll be able to feel the difference between say a 70 duro and 90 very easily.