yoke valve o-rings

[ajtoady]

I just picked up a bunch of spare o-rings for my tanks and am curious if I made the right decision. The o-rings are Viton with a duro of 90 . My question being will they be too hard or not. Usual duro for buna is around 60. My tanks are Faber 117 HP 3442 psi steels with the convertible valve, Yoke or Din. I use a yoke reg. I have been buying odds and ends to add to my save a dive box. Also would they work on the LP valves? Thanks, Tony

 

[herman]

No real need for viton but nothing wrong with using them either. 90 is the correct durometer for high pressure applications, 60 is too soft and prone to blowout.

 

[ajtoady]

I picked Viton for it's resistance to O2. Thanks for your input!!!

 

[Wookie]

Unlikely that they'll last long enough to be negatively effected by the O2 in your nitrox. I have neck O-rings that start to leak every 6 months or so, but the rate that most folks blow their face o-rings, the viton isn't worth the extra expense, especially if you are using convertible valves with the doughnut installed for yoke regulators. What I've had the best luck with as far as longevity goes are the Urethane 90 durometer o-rings for Sherwood 5000 valves. They seem to last forever, and are not as prone to blowing out as 70 durometer Buna o-rings. Those urethane o-rings are over a buck apiece. I don't use them in doughnuts.

 

[redacted]

Unlikely that they'll last long enough to be negatively effected by the O2 in your nitrox. I have neck O-rings that start to leak every 6 months or so, but the rate that most folks blow their face o-rings, the viton isn't worth the extra expense, especially if you are using convertible valves with the doughnut installed for yoke regulators. What I've had the best luck with as far as longevity goes are the Urethane 90 durometer o-rings for Sherwood 5000 valves. They seem to last forever, and are not as prone to blowing out as 70 durometer Buna o-rings. Those urethane o-rings are over a buck apiece. I don't use them in doughnuts.

It is good to have a few duro 90 urethane o-rings available in the event you encounter an extrusion problem in some application. Otherwise, the nitrile duro 90s at $.05 each are fine. I stick spares where ever I can find something to hold them like the yoke screw or dust cover string. I doubt if I have ever been to Bonair or Cozumel without using at least a couple.

 

[joystershell]

Hardness -- O-rings are normally available with a hardness rating, as measured by an ASTM type-A durometer, of 70 (the "soft" kind) or more rarely a rating of 90 (the "stiff" kind). The O-rings sold on this page are 90-duro (except for the -003 SPG O-ring), and well suited for the SCUBA applications we describe. The soft O-rings are appropriate for dynamic applications where the O-ring is providing a seal with a constantly moving part, such as inside regulators. The stiff O-rings are more durable in static applications where the O-ring is providing a seal with stationary or occasionally moving parts, such as a valve.

Oxygen Compatible O-Rings, Lubricant and Tools - Dive Gear Express