Scuba Pro S-Wing poppet o-ring

[NJDiver07866]

Just jumping in....Thanks everyone for the work.

I have been using for the past season on my scubapro poppet and don't have any issues... it is 2.5 instead of 2.2

From McMaster...
9263K546
(Same as 9263K11)
Metric Viton® Fluoroelastomer O-Ring 1 mm Width, 2.5 mm ID
In stock at $3.38 per Pack
This product is sold in Packs of 25

 

[Puffer Fish]

ok... I cannot believe that I actually went and looked up this issue.. I so need to get a life.

Here is some general design information that should help... just remember the tolerences change as the extrusion pressure go up:

Gland Dimensions

 

[Puffer Fish]

ok... I cannot believe that I actually went and looked up this issue.. I so need to get a life.

Here is some general design information that should help... just remember the tolerences change as the extrusion pressure go up:

Gland Dimensions

PS their viton o-rings are fairly nice... you just have to want 25 at a time.

 

[Couv]

ok... I cannot believe that I actually went and looked up this issue.. I so need to get a life.

Here is some general design information that should help... just remember the tolerences change as the extrusion pressure go up:

Gland Dimensions

Puffer Fish,

I too need to get a life... I went to the site you mentioned and also to eFunda eFunda: O-Ring Design Guidelines ...here is a quote from there re Radial Seals, "In order for the O-Ring to fit snugly in the groove, it is desirable to circumferentially stretch the O-Ring slightly. The recommended amount of stretch is between 1% to 5%, with 2% as the preferred stretch value. "

Therefore if you have a groove and you want to know the best suited o-ring i.d. size for it, you measure the groove o.d. and subtract 2% to get the ideal o-ring i.d. for it.

I.g. the poppet groove is 0.091 2% of which is 0.00182, find the difference (.08918) to find the ideal i.d. of the o-ring. Converted to mm (2.26517) we are well with in the parameter with our 2.2 i.d. o-rings.

.....now I can get some sleep at night.

Edit: I just checked an old style (blue plastic with metal stem) Scuba Pro poppet stem and it mic'd to .095

Couv

 

[HenrikBP]

Way above my understanding of these issues. But thanks for taking the time to look and for keeping us in the loop.

Henrik

 

[Texfrazer]

Hey Guys,

I ran across a draft copy of that explains in pretty good detail about the 2 o-ring poppet. Apparently, it was designed for the G500, but was also used to replace the old poppets in the R156, G200B and G250.

The 2 poppet has 2 different diameters where the o-rings sit (we already knew that). The groove closest to the seat is deeper in order to reduce friction and to help allign the stem. The 2nd o-ring is the sealing o-ring. The space between the o-rings is said to be used as a trap for lubricant in order to keep them from drying out.

Of note is that couv's measurements above show the inner groove to be the smaller one (largest diameter). I wonder if another change was made later on?

Interesting!

 

[Zung]

I love that bottom line: "Only SCUBAPRO o'rings should be used... Failure to use the appropriate o'ring... could lead to injury or death"

 

[aquaregia]

My college's generic recreation waiver has the death and dismemberment clause in it. While it made sense for SCUBA, fencing, martial arts, etc, I remember being fairly shocked by it when I took a chair massage class...

 

[Couv]

Of note is that couv's measurements above show the inner groove to be the smaller one (largest diameter). I wonder if another change was made later on? Interesting!

Actually, I think the difference is just in the terminology.....when I say the inner journal is larger, I mean the deepest in the balance chamber. The larger journal expands the o-ring more to make the seal. Have a look at the poppet in the diagram you posted, the larger journal is on the end that goes deepest into the chamber and the other o-ring journal allows more slack in the o-ring in order to serve as a wiper rather than a seal.

......The journal with the o-ring that first goes into the balance chamber is slightly larger than the other one. I checked it with my dial calipers and found that the larger one is approx 0.091 inches and the smaller one at approx 0.077... Awap suggested a while back that one o-ring could be serving as a wiper as the other holds the pressure, but I would think even if that were the case, if the primary failed, the other should be able to serve as a backup.....

I love that bottom line: "Only SCUBAPRO o'rings should be used... Failure to use the appropriate o'ring... could lead to injury or death" <http://www.scubaboard.com/forums/images/smilies/Standard%20Smiles/03.gif>

I like the way they explained in a roundabout way why they use a cheaper material for the o-ring itself....."These changes have
been implemented to help prevent/reduce price increases......."

Tex & Zung.....keep those great attachments coming....thanks

c

 

[Zung]

Actually, I think the difference is just in the terminology.....when I say the inner journal is larger, I mean the deepest in the balance chamber. The larger journal expands the o-ring more to make the seal. Have a look at the poppet in the diagram you posted, the larger journal is on the end that goes deepest into the chamber and the other o-ring journal allows more slack in the o-ring in order to serve as a wiper rather than a seal...

c

Right on couv!
SP did the same with the composite piston of the MK20/25. They stated in the Engineering Bulletin #267: "... And additional piston head o'ring has been added which protects the "main" o'ring from debris, and helps trap lubricant... To reduce friction, the (additional) o'ring is recessed... The effect... is to seal the compression chamber...".