Why has Aqualung banned viton o-rings ?

[Ome Ko]

The use of Viton o-rings is not authorized by Aqualung and Apeks.
Anyone knows why?

 

[anzac65]

The use of Viton o-rings is not authorized by Aqualung and Apeks.
Anyone knows why?

Yes. Aqualung and Apeks do.

 

[potablewater]

I think my Apeks xtx50's/DS4's and hoses all came with Viton O rings!?
If they are no longer supporting this equipment part, then why and what is the alternative. I also have a save a dive kit with backup Viton's as I thought that was the recommendation. Please tell me more...
Thanks.

All the best,
Geoff

 

[captndale]

Ever since nitrox was introduced to the sport diver market Viton has been used inappropriately. Viton makes a good seal and is resistant to oxidation but has very poor resistance to abrasion. It should never be used in dynamic applications (applications in which there is movement). It will wear out quickly and could cause regulator failure.

 

[ClayJar]

I also have a save a dive kit with backup Viton's as I thought that was the recommendation.

Viton on hose fittings and valves is no problem. Those are basically "static" applications (i.e. you tighten them once and then they stay put).

On the other hand, inside your regulator there are O-rings you'll never see unless you're looking at all the little pieces during a rebuild. Those O-rings slide back and forth with each breath or burst of air. They're called "dynamic", as they keep moving, not just once when you're putting it together.

Viton O-rings have excellent qualities for dealing with high oxygen concentrations in static applications, but if you try to use them in dynamic applications, apparently they'll wear out too quickly. Other O-ring materials have better oxidation resistance than nitrile ("plain old") O-rings *and* better abrasion resistance than Viton O-rings, so I imagine one of those would be used for the dynamic applications *inside* the regulator.

 

[captain]

EPDM most likely, it's all I use, very abrasion resistant.

 

[redacted]

Ever since nitrox was introduced to the sport diver market Viton has been used inappropriately. Viton makes a good seal and is resistant to oxidation but has very poor resistance to abrasion. It should never be used in dynamic applications (applications in which there is movement). It will wear out quickly and could cause regulator failure.

Parker Bros rates Viton good to excellent (GE) for dynamic properties, along with nitrile and EPDM. For abrasion resistance, EPDM is rated GE while viton and nitrile are both G. Vitons one clear weakness is tear resistance where it is only rated Fair, so I guess if there is an extrusion problem, the viton may tear easier than other options. I understand that for a while Scubapro was using polyurethane o-ring in dynamic HP applications. They are a bit more expensive but are rated E for dynamic properties as well as tear and abrasion resistance.

BTW, ozone resistance is E for viton, EPDM, and polyurethane but Poor for nitrile. I still have nitrile o-rings in some of the regs I use for nitrox and have had no problem. At my age, they may still last longer than me.

 

[Hallmac]

Viton produces an extremely hazardous gas when burnt. The current EPDM o-rings handle Oxygen and do not produce the toxic gas if a disaster occurs.

 

[PhilEllis]

I am going completely from memory here and have not search to validate this this morning, but I also seem to remember that "if" there is a heat even with Viton o-rings, there is the possibility of a gas emission that is not "breather friendly". Maybe some with better chemical understanding than me can research or explain this further.

Phil Ellis
Discount Scuba Gear at DiveSports.com - Buy Scuba Diving Equipment & Snorkeling Equipment