O-rings, O-rings

[oxyhacker]

95% of the time you can get away with a good quality generic 70 duro (that's the most common hardness for O-rings, and the one you'll usually get if no hardness is specified) nitrile aka buna-n O-ring. I say good quality because there are a lot of cruddy imports around too - like the one in those cheap bargain import assortments and maybe the tray at your local hardware store (LHS?). They work too, but seem to age crack and break down a lot faster.

The generic O-rings you'll run into most often are the AS 586 series, often called the 2-dash series since each size code is prefaced by a 2-. Get a a size chart (there's one on page 129 of my book) or catalog (Parker has a good one) to identify the ones you need since you'll usually have to order by the 2- size code rather than the actual size.

A few regs like Apeks and some of the newer Italian-designed SPs use metric sizes, something to be aware of when when you can't find the right O-ring in the 2- sizes. Though it is suprising how often someone who doesn't know this will plunk in the nearest inch size and get away with it.

There are a few applications where a special ring is required or desirable - usually a harder 90 duro, or maybe oddball material like urethane to resist extrusion - like the HP O-ring on piston regs.

Jamiei, I try not to push my books too hard here, but I got to laugh this time, because of all the many reg servicing questions you've posted here (or sent me privately) I bet about 98% are answered in my reg book which you never seem to be able to bring yourself to buy (and which just may be why "everyone else knows it" ;-)

jamiei once bubbled...
Anyone have any valuable information on O-rings? Can you use "generic", where to get them, whats the durometer, material variations? I'm surprised their isn't more discussion about them... or does everyone else just know it all?SNIP

 

[Genesis]

for a reg intended or high FO2 service though? I thought Viton was the preferred material there...

 

[FredT]

Genesis once bubbled...
Hardness can be measured if you have the appropriate equipment.

O-ring hardness is almost never measured directly. The shape of the ring causes problems with the tooling indenter giving some pretty wild readings. Generally there is a "standard" sprue block formed at the same time as the rings. This block is used to characterize the hardness of the rings coming out of the mold on that shot. O-ring molds may have one or hundreds of cavities per shot depending on size, production volume and materials.

As far as the ring numbers go, for SP first stages you'll need most of them from 2-010 through 2-018, plus the piston ring. For markV and clones (IDI, Beauchat, Oceanic, and others) I believe that ring is a 2-021 or 2-022 (I'd need to confirm that last before I bought more, but I have about 40 left.)

Viton rings come standard in 70 and 90 duro, neoprene comes in 40 through 70 duro as standard, with most rings sold being 70s in both materials. For a captive static seal ring on good surfaces 70 or 90 duro rings are interchangeable in most applications. Piston seal and piston shaft seal rings should be softer to ease the "dither" and reduce ring wear in use. Even viton 90s will work there if the reg is going to be serviced regularly.

Hose fitting rings most commonly used are 2-903 (3/8-24 thread)through 2-906 (9/16-18 thread)

Tank yoke rings are 2-014 (skinny) The fat ring is a 2-111. Valve stem o-rings (if used) are 2-010.

Tank valve rings for a 3/4-14 NGS valve is a 2-214.

The basic rule when working on any pressure gear is to never re-use a ring that has seen pressure and then been disturbed. ANY felt problem during reassembly requires disassembly and replacement of the ring before proceeding. Sharp edges can shave rings VERY easily, and the shaving (not necessarily the ring) can cause real trouble later. Examining the removed ring and recovering the ENTIRE ring is very important in a possible shaved ring situation!

FT

 

[jamiei]

Mech, i'm not talking about an o-ring from walmart. I'm talking about a high quality, hardness tested o-ring. I am also currently working on such a cross-reference for Scubapro 0-rings Genesis and have quite a few that I'm locked up on and have purchased for average of $0.32 each. From what I've heard, around 70 durometer for LP rings and 90 durometer for HP rings will work fine. Also, these 70 durometer o-rings are nitrile and the 90 durometer should be urethane. I have a scubapro oring chart that is to scale that helps a lot. I also have verified this with parts from actual service kits. The company I am dealing with is Lawson Products and they have I think 8 distribution centers and one just happens to be 50 miles from me. Prices are great and all I do is give them a call.

O-ring... I had to post this thread cause I new that would be your response...

Oxy... You are correct, I have yet to buy your book... and I do intend to, but buying it just seems too easy. I have to go about things the hard way. I also have come into possession of a sp technical service manual and tech education workbook that has kept me from buying your book because I really haven't finished wading through all the info I have. However, as I'm sure you'll note, scubapro doesn't really care for their techs to know that much about o-ring hardness and cross-referencing them because they assume they will only use the SP kits.

As a last note, I do know much more about these little things than I may have given the impression to have, but I firmly believe there's always something you don't know... and thats why we're all here and why we all check threads like this. Take the dog to obedience class and look what happens...

One other thing, the viton o-rings I saw came in 75 and 90 durometer and weren't offered in 70... not much difference really. Lawson also has a few metric sized o-rings and in many scubapro service kits, you'll find metric numbers. They sell them in packs of 10 also.
One other question... i've heard mention of the shelf life of service kits... anyone have any real, first hand experience here other than rumors? If this is the case, and they do only have a limited shelf life, why don't these things have an expiration date like milk? Guys, I just love to see people talking here about things that make me tick and this is one of them. Sometimes the board seems to get a little slow and drifts far away from topics like this. To some, this may be a little boring, but there are new people here everyday that are soaking up stuff like this like a 20lb sponge. I was like that, still am, and hope I never change.

just remember, an iquisitive mind is a sign of intelligence

 

[Genesis]

seal those O-rings in a vac-packed bag. Then store them in a dark, cool place and they'll last damn near forever.

Got an online source for those folks? Or are they "phone in/walk in" only?

A list of those O-rings and cross-references to SP parts would be fan-flipping-tastic!

The only thing "hard" to get would then be seats....

 

[Dectek]

Lawson products are a large supplier in the car dealer and repair business. You might want to check with your local mechanic and see if a Lawson salesman drops in every once in a while.
If not....check out their website.
http://www2.lawsonproducts.com/website/main.nsf

I had an Oring discussion with a LDS owner tonight and he stated that he uses the highly overpriced pre- packaged orings from the manufacture and will not mix match or cross- reference because of liability. He said that if a diver's next of kin tries to sue he can go right to the work order and show that he ONLY uses what the Manufacture gives him to use in the kit.( AKA Pass the Buck).

Funny that it was brought up about a book purchase.. I was looking at the airspeed press site just before Christmas and added Oxy-Hackers, Repair and Maint, and canister lights to my Santa list but my girlfriend and siblings did not get me any of the books. When I asked about the lack of reading material under the tree, I was a little shocked at the answer.
"I knew you would not spend $115 for a couple of books so I figured better be safe and not spend it until I was sure if was safe."
Damn it....that is why I told them about the books in the first place.

Wonder if I could get a discount when purchasing more that one book?

 

[jamiei]

you can call in and order, I did. The seat could be duplicated if its not available for some other, not so "regulated" use. Let's face it, this seat only needs to be of the appropriate material and hardness. If you could buy this in sheets somewhere, like most manufacturers probably do and you're good with an exacto (don't have to be too good to trace) or even maybe buy a die of the right size then you could probably keep yourself in a good supply of seats forever. A little experimentation would be in order to make sure your seat seals up reliably. These seats aren't made of some scuba industry unique material, I'm sure. As has been said, if you have a source of seats or service kits by all means get those and save yourself some time trying to make a seat. My intent in this post is to have a cheap source of many of the o-rings that don't come in a service kit (static), but is probably best to change regularly if you have access to them. I just don't see buying 2-3 o-rings from a guy and paying $15 or so when I can get them for $0.32 each. For $0.32 I will replace them often. One last thing about lawson products, they don't carry any 90 durometer o-rings, only 70 durometer buna-n and 75 viton. They can possibly special order these from elsewhere, but your best bet is to find another source for these.

 

[FredT]

Check the phone book for bearing and hydraulic equipment houses. Cunningham Bearing, Dixie Bearings, Motion Industries, ABS and others bearing houses carry seals. Larger cities will often have a direct Parker Seal representative. These can be found through:

http://parker.com/sg/parkerseals/salesoffices.asp

National Seals and several others also have sales reps nationwide. Be aware that quantity discounts kick in fast on o-ring sales. 50 rings are often only twice the bottom line price of 10

HP Seats can often be made by getting the correct diameter teflon or hard urethane rod material from a plastics house and parting it off on a lathe or drill press. This is much faster than cutting them out of sheet unless the seat is really thin. I tend to resist making seats but the "old style" MkV clone teflon seats are getting hard to find. Most machne shops can duplicate a seat rather quickly, but you'll want to get a bunch of them at a time to cover the setup charges.

FT

 

[jamiei]

Ran across something I found kinda interesting that shows the manufacturers motives... Directly from scubapro... "The "splined" swivel hose fitting helps to prevent consumer disassembly. right from their book. We all knew this anyway... its obvious but they put another spin on it. They try to fool the tech into believing this is the man reason for the splines when in fact, its two-fold. Keep the unmotivated customer from working on his regs and make the tech buy a $30 tool so they don't scratch up the fitting. Makes it a necessity...

 

[Stone]

Jamiei,

If you haven't seen this site before, go to Mike's Scuba and browse through the Scuba Store. There are tons of accessories, tools, and parts (including O-rings and few HP seats). I don't know if the prices are competitive, but it is still a neat place to look around.

This is mostly Trident stuff, but since Trident doesn't sell directly, Mike's Scuba may be a good outlet.