Identify aqualung oring

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scubaalblake

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I have 5 aqualung Cousteau first stages (aka conshelf SEA)
They are great regs and just go on and on.
Most of the orings are standard sizes eg 010, 011, 013 Etc BUT there is an oring at the base of the first stage that is not a standard size.
Aqualung part number is 824407 and in the service kit shadow diagram is seems to be exactly the same ID as a 013 but made of slightly thicker material.
Any idea what it is?
I am sure aqualung don't make one oring themselves of a size only known to them:)
If it's not a standard AS568A size - what other size range could it be from. Seems to be used in a lot of Aqualung regs. I have lots of spares of the other orings Hp sets etc, but if I can't find out what this oring is and buy it separately I'm faced with buying first stage service kits for 1 oring!
 
I am not familiar with AL but you hit one of my favorite subjects: parts compatibility.

It looks like a static application so; if the shoe fits, wear it.

What happens when you use an -013?

Have you tried a -111? How about a -110 stretched a bit? A -905 is another possibility. Or, in metric, an 11mm ID, 2mm W.

Silly to buy a kit for one $.05 o-ring. I have static o-rings that have been in use for about 20 years with no problem.
 
Thanks for the reply. Unfortunately when I use a 013 it can blow out. Given that its HP at the base of the first stage that's pretty drastic! So its 'nearly' an 013 but not quite:)
Was just reading another thread and it seems like there is a UK oring size range.....gone see if I can wrap my brain around seeing whats the closest to an 013 in that range.
 
As awap suggested, you may want to look at a metric O-ring.

Metric O-rings give you a large variety of options. In that range you can get 10 mm or 11 mm ID with a variety of thickness combinations, in 0.5 mm increments.
The 11 mm ID by 2 mm thickness is very close to the -013, but just a bit thicker.

11 mm = 0.433 inches
2 mm = 0.078 inches

The -013 is 0.426" x 0.07"
 
yep I reckon thats it.
Ive just measured the dimensions on the shadow sheet for the last service kit I got and it lines up with
ID 11mm
Thickness 2mm
OD 15mm
which is a metric size. Best of all simplybearings in the UK seem to have that size in stock in Viton - so Im ordering 10!
 
...Unfortunately when I use a 013 it can blow out. Given that its HP at the base of the first stage that's pretty drastic!... So its 'nearly' an 013 but not quite:).

To clarify I have attached the exploded view of the 1st stage in question. Its part number 20 your looking for right?
 

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yep sure is.
ive done some investigating and i am pretty sure that its a metric 11mm oring.
ID 11mm
Dia 2mm
OD 15mm

Using my micrometer that seems to match the shadow picture from an old service kit I have (dont have the oring any more). That would make it almost the same as 013 - but a little fatter...which seems right.

(013 is 10.82 ID 1.78 Dia, 14.38 OD)

Im going to my local oring supplier tomorrow to see if they have M11 Viton 90 Shure.
If not i'll get them from simply bearings in the UK, who have them online - but only 75 Shure :(

- anyone got views as to using 75 Shure orings for static seals if you cant get anything else?

While we are talking parts I have Cousteau DIN valves and they take an unusual filter - 106326. Its a flat filter but *smaller* than the one on all the other yoke conshelfs. Seems pretty hard to get.

Any ideas anyone?
 
...Unfortunately when I use a 013 it can blow out. Given that its HP at the base of the first stage that's pretty drastic! So its 'nearly' an 013 but not quite.....
....Any ideas anyone?


I had one of these where the plug (21) wouldn't seal too. After much agony I figured out the reg had been dropped and body around the plug was bent just enough for the oring to not seal. It looked oval, not circular.
 
Im going to my local oring supplier tomorrow to see if they have M11 Viton 90 Shure.
If not i'll get them from simply bearings in the UK, who have them online - but only 75 Shure :(

- anyone got views as to using 75 Shure orings for static seals if you cant get anything else?

The design of a dynamic O-ring requires some clearance for the moving parts and therefore there is always some possibility of extrusion. In this situation, a higher durometer O-ring (such as 90 durometer) can be beneficial.

The design of a static O-ring like the one in the diagram can normally be done with minimal to no clearance that would allow the O-ring to extrude. A well designed O-ring groove in this geometry should have metal to metal contact and the O-ring would never extrude (if properly designed and properly assembled). Therefore there is really no need for the higher durometer even for high pressure applications.

There is actually a very good argument for always using lower durometers for static O-rings (for a properly designed captive O-ring). The lower durometer rubber will conform to any imperfection on the sealing surface better than the stiffer O-ring. The softer rubber, therefore should create a more reliable seal with parts that are less than perfect (as long as there is enough compression on the rubber).

In practice I have had good luck trying to salvage prototype parts that had less than perfect O-ring sealing surface by using slightly fatter O-rings of 70 durometer. These were high pressure sealing surfaces with slight surface undulations caused by the machining process.


I always use 70 durometer O-rings with only a few exceptions and then only for high pressure dynamic O-rings.
 
To clarify I have attached the exploded view of the 1st stage in question. Its part number 20 your looking for right?

That first stage was made at the Spirotechnique plant in France so you are probably looking at a metric size O ring.
 
https://www.shearwater.com/products/peregrine/

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