O-rings

[Creed]

Is there a significant difference between Buna and Viton o-rings? The Viton seems to be a lot more expensive. Is it a better o-ring material? And if it has an increased life, does this matter on a regulator that has a yearly overhaul anyway?
Update: I just ran across an advertising blurb that says that Viton is better for "oxygen compatibility." So, is Viton preffered for Nitrox applications?

 

[redacted]

Buna is not recommended in a high O2 environment. My understanding is that they will degrade more rapidly than in 21%. Viton was the material of choice for nitrox use but I believe EPDM is what many are using now. EPDM is quite abit cheaper. One advantage that keeps me using viton for o-ring that I don't use many of is it is supposed to have a longer shelf life (up to 20 years). Otherwise, I use EPDM.

For lower quantities at good prices, try:
http://www.air-oil.com/oringsonlinefset.htm

These are o-rings of unknown breeding but seem to work OK. Only problem is high duro only available in buna.

 

[jbd]

As noted by awap, it is my understanding that the BUNA rings don't hold up as well to high O2 exposure. I would have to get my manual out and check but I believe that Viton rings produce less heat when they burn than the BUNA. I'll see if I can track down that info later today just in case I might be highly confused.

I recently O2 cleaned four tanks and valves and replaced the O-rings with viton. Cost was less than $7 total. The rings were purchased locally.

 

[FrankT]

On the subject of O-rings. What Durameter should be used for locations like valve to tank neck and hose connections? 90?

 

[redacted]

On the subject of O-rings. What Durameter should be used for locations like valve to tank neck and hose connections? 90?

I'm using V75 for those applications. Only place I use 90's is HP piston o-rings. It's not that I think 90's would be wrong for those applications, they are just harder to come by.

 

[DA Aquamaster]

Viton does not seem to hold up as well in dynamic applications where they are subect to wear and are less tolerant of inadeuate lubrication in static applications.

Viton is less susceptible to buring in a high o2 environment but produces phosgene gas when it does. Phosgene was one of the poison gases used in WWI, so an o2 fire while you are brething on the reg would be a very very bad thing with viton o-rings.

I used to use them in O2 regs before SP switched to EPDM o-rings but I now use EPDM o-rings and am much happier with their longevity.

 

[Creed]

I admit to being baffled. I was going to order some orings from www.air-oil.com, but I am having trouble finding the sizes I need. I wanted to get a set of these sizes:
003,010,011,012,013,014,015,111,112,214

The only match I have found so far is the dash size. For example, they have a dash size of "2-003 E70" listed. Would this be a 003 oring?

 

[redacted]

I admit to being baffled. I was going to order some orings from www.air-oil.com, but I am having trouble finding the sizes I need. I wanted to get a set of these sizes:
003,010,011,012,013,014,015,111,112,214

The only match I have found so far is the dash size. For example, they have a dash size of "2-003 E70" listed. Would this be a 003 oring?

Yes, your numbers are the last three difits of the 2-###. What regs are you planning on servicing?

 

[Creed]

Yes, your numbers are the last three difits of the 2-###. What regs are you planning on servicing?

Conshelf XIV's. I don't know the history of the regs, so in addition to the parts from the rebuild kits, I was going to replace all of the hose orings as well. And since that website has decent pricing, I was going to build up a store of orings for my save-a-dive kit at the same time. The numbers I quoted were pulled from the list of another oring save-a-dive kit, so if you have any suggestions regarding that, let me know.

 

[grouchyturtle]

According to McMaster Carr (page 3223)
EPDM has a higher resistance to salt water too.