O-ring obfuscation

[JB]

I just did a bit of research on the basic o-rings we kind of take for granted (now you know how bored I was, I was actually trying to put together a few spares for a trip)- LP port 011, HP port 012, 2nd stage swivel 010, DIN 112. Instead of measuring, I trolled through the service manuals of those manufaturers who publish the exact size of their o-rings, almost all 3 had different sizes for the same application. For interest here is a summary, I guess if the "standard" doesn't fit your reg try one of the other manufacturers "standard". This has left me with several questions. I wonder if the dive shops and/or service centers are obsessive about which one to use with which brand? In terms of the ports, is the o-ring spec. related to the design of the port or the hose? Since they are so close in measurement, does it really matter? I wonder what the most common specs are? Since the most common brands don't publish their specs this is difficult. Finally in the interests of safety these should be published, good on these brands for not colour coding, or using obscure part numbers.

Site Measurement BS-number Standard

SPG Spool 1.42 x 1.52 BS-003

LP port 7.65 x 1.78 BS-011 Zeagle
6.75 x 1.78 BS-610 Beuchat
7.65 x 1.63 BS-903 Oceanic

HP port 9.25 x 1.78 BS-012 Beuchat/Zeagle
8.92 x 1.83 BS-904 Oceanic

2nd stage swivel 6.07 x 1.78 BS-010 Oceanic/Zeagle
6.35 x 1.78 BS-803 Beuchat

DIN valve 12.37 x 2.62 BS-112 Oceanic
11.92 x 2.62 BS-614 Beuchat
10.77 x 2.62 BS-111 Zeagle

Tank neck
25 mm 25 x 2.95 BS-913N90
¾ inch 25 x 3.53 BS-214N90

YokeThin 12.42 x 1.78 BS-014 N90
Thick 12.37 x 2.62 BS-112N90

 

[captain]

O rings by any manufacture are made to a standard specification, here in the US it would probably be an ASME ( American Society of Mechanical Engineers) specification so what company made it should not matter. Regulator designers and for that matter any designer of a mechanical devise designs it around common engineering standards. It would be too costly and chaotic if every devise required a custom made sized O ring, bearing , seal etc size.
The main issuers are is the O ring made to a US inch specification or a a metric millimeter specification, some are very close but not exactly the same. other than that it would be material and durometer rating (hardness).

 

[Zung]

I dive Scubapro only, so here's yet another set of "standards":

• HP port: 2-011, EPDM 85
• LP port: 2-010, EPDM 70
• DIN: 2-111, EPDM 85

I guess it has something to do with the size of the groove, and the fact that the rubber can take quite a bit of stretching.

 

[Codiak]

I dive Scubapro only, so here's yet another set of "standards":

• HP port: 2-011, EPDM 85
• LP port: 2-010, EPDM 70
• DIN: 2-111, EPDM 85

I guess it has something to do with the size of the groove, and the fact that the rubber can take quite a bit of stretching.

If you interested in O-Ring fundimentals I found the follow to be a nice primer.

http://www.thesealman.com/pages/orin...g_handbook.pdf

 

[emoreira]

If you interested in O-Ring fundimentals I found the follow to be a nice primer.
http://www.thesealman.com/pages/orin...g_handbook.pdf

The link is broken.

 

[captain]

I dive Scubapro only, so here's yet another set of "standards":

• HP port: 2-011, EPDM 85
• LP port: 2-010, EPDM 70
• DIN: 2-111, EPDM 85

I guess it has something to do with the size of the groove, and the fact that the rubber can take quite a bit of stretching.

That is three different sizes and two different durometer hardnesses, 85 being the harder of the two. Personally I don't think the difference between 70 and 85 on the LP and HP port makes a bit of difference or much sense, just use 85 on both.

 

[Blue Sparkle]

The link is broken.

I believe this link will get you to the main O-ring Handbook page with several downloading options:

O-Rings, Materials, Metric, Inch, Groove Dimensions

 

[Zung]

... Personally I don't think the difference between 70 and 85 on the LP and HP port makes a bit of difference or much sense...

Neither do I.
It's the size that always surprises me, even after the extensive lecture couv gave me: one size up or down doesn't seem to make a difference

 

[JB]

I dive Scubapro only, so here's yet another set of "standards":

• HP port: 2-011, EPDM 85
• LP port: 2-010, EPDM 70
• DIN: 2-111, EPDM 85

Zung, is that a Scubapro specification, where do they specify these things? I was not aware that you could get EPDM harder than Sh80. (Certainly can't make Sh90 out of EPDM) Seems that Zeagle and Scubapro use the same LP and HP port sizes, but a different DIN? I would have thought the 3/8 and 7/16 ports as well as the DIN connector would be industry standards. When you buy a new hose it generally comes with an o-ring in situ, what size is that one?

 

[Bubbletrubble]

Zung, is that a Scubapro specification, where do they specify these things? I was not aware that you could get EPDM harder than Sh80. (Certainly can't make Sh90 out of EPDM) Seems that Zeagle and Scubapro use the same LP and HP port sizes, but a different DIN? I would have thought the 3/8 and 7/16 ports as well as the DIN connector would be industry standards. When you buy a new hose it generally comes with an o-ring in situ, what size is that one?

@JB: AFAIK, there are 2 different sizes for the "external" o-ring on a DIN-configured first stage: -111 = smaller size (e.g., Apeks), -112 = standard size (e.g., Aqualung, Scubapro, etc.). I recommend keeping both sizes in your save-a-dive kit.

AFAIK, the o-rings on port plugs and hoses that screw into the LP (3/8 UNF) and HP (7/16 UNF) ports on a first stage are standard sizes: -010 = 3/8 UNF, -012 = 7/16 UNF.
Bear in mind that some first stages have one slightly larger LP port (1/2 UNF). The port plug and hose (or adapter fitting) which screw into this larger LP port take a -013 o-ring.