Viton vs Nitrile O-rings...

[wreck-tekkie]

Hi all,

I'm cleaning my own tanks and valves and I'm wondering what your opinion is about nitrile (Buna-N) O-rings used with nitrox. Everybody recommends Viton in valves and regs that are in contact with Nitrox but they are so ********** expensive and hard to get.

I think you can just use nitrile O-rings for nitrox less than 40% even if you do partial pressure blending because the time the O-ring is in contact with pure oxygen is just minutes during the filling process. For (deco) mixes above 40% I agree to use Viton although there also discussions regarding that.

What's your opinion?

Thanks and cheers
Duncan

[awap]

I usually go for EPDM. All the favorable characteristics of Viton at a much more reasonable price. I have no problem with using nitrile in my regs but I don't think I would use them in my nitrox tank, at least not any that see constant exposure.

[NJDiver07866]

I tell you what.. Awap turned me on to McMaster-Carr this site..

I can't thank him enough..i stocked my box for under $50 bucks.. and I'm pretty much set for life.
Size chart...

AS568B- Outside Diameter SCUBA Application Seal
214 1-1/4 Cylinder with Large Neck/Valve (3/4 NPS - All Aluminum, most Steel cylinders)
116 15/16 Cylinder with Small Neck/Valve (7/8 UNF - "Genesis" 3500 psi Steel cylinders)
112 11/16 Standard DIN Regulator/Valve (Nearly all DIN regulators)
111 5/8 Small DIN Regulator/Valve (You know if you need this one)
015 11/16 Cylinder Valve Bonnet Nut
014 5/8 Standard Yoke Regulator/K-valve
013 9/16 Large Low-Pressure Port/Hose (1/2 UNF)
012 1/2 High-Pressure Port/Hose (7/16 UNF) Manifold and Manifold Port Plugs
011 7/16 Standard Low-Pressure Port/Hose (3/8 UNF)
010 3/8 Low-Pressure Hose/2nd Stage Regulator Cylinder Valve Stem
003 3/16 High-Pressure Hose/SPG swivel

[DIWdiver]

NJDiver -

That list is great! Thanks.

Here's another place to buy o-rings. You can get them a lot cheaper than McMaster Carr.

Welcome to the AOP Technologies, aerospace, pneumatics, o-rings

My buddies at Privateer Divers say they pay even less at Parker. I think they mean Parker-Hannifin. But they have an account.

D

[mts0628]

NJDiver -

That list is great! Thanks.

Here's another place to buy o-rings. You can get them a lot cheaper than McMaster Carr.

Welcome to the AOP Technologies, aerospace, pneumatics, o-rings

My buddies at Privateer Divers say they pay even less at Parker. I think they mean Parker-Hannifin. But they have an account.

D

I use AOPTec as well and I have a ton of o-rings. I still buy the overhaul kits for my regulators, but everything else- lights, spare o-ring kit, power inflator overhaul, DIY divelight build, I have AOPTec o-rings on hand- and forever. The prices are awesome too.

[skdvr]

NJDiver -

That list is great! Thanks.

Here's another place to buy o-rings. You can get them a lot cheaper than McMaster Carr.

Welcome to the AOP Technologies, aerospace, pneumatics, o-rings

My buddies at Privateer Divers say they pay even less at Parker. I think they mean Parker-Hannifin. But they have an account.

D

The only thing about the above site is that they do not sell 90 Duro O-Rings. I put 90 Duro on all captive o-rings. and 70 or 75 duro on all dynamic o-rings....

I too buy o-rings from McMaster-Carr

Phil

[DIWdiver]

The only thing about the above site is that they do not sell 90 Duro O-Rings. I put 90 Duro on all captive o-rings. and 70 or 75 duro on all dynamic o-rings....

I too buy o-rings from McMaster-Carr

Phil

Actually, they do sell 90 duro, but only in nitrile.

D

[fppf]

I get my O-rings from Grainger, they have durometers and materials needed.

Do not use nitrile orings in any application where pure O2 is used. It only takes a fraction of a second to combust.

Also durometer is not a function of type of seal, its a function of seal type, pressure, and clearance.

[halocline]

Hi all,

I'm cleaning my own tanks and valves and I'm wondering what your opinion is about nitrile (Buna-N) O-rings used with nitrox. Everybody recommends Viton in valves and regs that are in contact with Nitrox but they are so ********** expensive and hard to get.

I think you can just use nitrile O-rings for nitrox less than 40% even if you do partial pressure blending because the time the O-ring is in contact with pure oxygen is just minutes during the filling process. For (deco) mixes above 40% I agree to use Viton although there also discussions regarding that.

What's your opinion?

Thanks and cheers
Duncan

I'm fairly sure it's aviation standard practice to use nitrile o-rings in 100% O2 environments, so I would not be too worried about it. OTOH, if you're doing tank valves, you only replace the big tank neck one every year. Any that might be in the valve (I guess it depends on the valve design) could last years. My point is that viton is not that expensive, given you need one per tank per year. That's quite a bit less money than a couple of air fills. EDPM would work fine as well, and is (I think) the same price as nitrile at oringsusa.com.

Couv knows a lot about o-rings and works in the aviation field, maybe he'll chime in.

[fppf]

I'm in aerospace, for oxygen service Viton is used.