Old regs, worth playing with?

[captain]

Hello DeadlyRisk,

Someone here should know the correct o-ring sizes and hopefully will post them and make the rest of the following garbage moot.

I probably do not need to tell you it is unwise to measure old o-rings in order to find the size needed. If memory serves me correctly, you should be able to determine the correct size by measuring the groove outside diameter (O.D.) Note that o-rings should be slightly stretched (1-5% with 2% being recommended) Therefore, after you measure the groove, multiply by 0.98 to find the inside diameter (I.D.) of the o-ring you need. Almost all regulator o-rings have a cross section (c.s.) of 1/16" therefore any o-ring with a 0 after the dash will have a c.s. of 1/16 and that make finding the correct seal pretty simple.

For instance, if you measure the small piston groove and get a dimension: 0.116 multiply by 0.98 to get the I.D. 0.11368 you need and find the closest match with a dash number of 0 at a site like What is AS568A? and you come up with a -006.

We Usual Suspects like to debate over the material, but I think most of us agree you cannot go wrong with Viton or EPDM. For hardness in low pressure applications 70-75 is fine, for high pressure go with 90.

......now where did I put that Parker manual?....

Couv

Usually there isn't enough difference in in size between an old O ring and the same size new O ring to confuse it with the next larger or smaller size new O ring.

 

[deadly_risk]

Usually there isn't enough difference in in size between an old O ring and the same size new O ring to confuse it with the next larger or smaller size new O ring.

Okay, taking that thought I re-measured everything latest data in the attachment.

It seems like the Aqua-Lung part number correlates to a possible o-ring size, is there a precedent for this? Or is this how it normally works?

For example: part number 8200-11 has a estimated ID of 6.96mm, measured ID of 8.24mm, and AS568A-011 has a ID of 7.65±0.13. The difference given the stated error is 0.46mm.

Edit: or if we take the estimated ID value of 6.96mm and the error of using AS568A-011 is 0.56mm.

Is that close enough to assume the parts numbers correspond to o-ring sizes?

 

[Paladin]

Okay, taking that thought I re-measured everything latest data in the attachment.

It seems like the Aqua-Lung part number correlates to a possible o-ring size, is there a precedent for this? Or is this how it normally works?

For example: part number 8200-11 has a estimated ID of 6.96mm, measured ID of 8.24mm, and AS568A-011 has a ID of 7.65±0.13. The difference given the stated error is 0.46mm.

Edit: or if we take the estimated ID value of 6.96mm and the error of using AS568A-011 is 0.56mm.

Is that close enough to assume the parts numbers correspond to o-ring sizes?

Please check my last post. The last three digits of the part number is the O-ring size.

 

[deadly_risk]

Please check my last post. The last three digits of the part number is the O-ring size.

Ah, I completely missed it. Well, that makes buying o-rings pretty easy now.

 

[Paladin]

Yep. And I have a couple of lines out for replacement HP seats, too. I'll let you know as soon as I find out.

The second stage low pressure seats are the same ones AL still uses and even the diaphragms are still being used in some of their current second stages.

I took my #1 Aquarius (the one I bought new in 1978) over to the lake for a solo outing yesterday. It performed flawlessly, as always.

 

[deadly_risk]

For hardness in low pressure applications 70-75 is fine, for high pressure go with 90.

So can it be assumed everything in the first stage should be 90, everything in the second should be 70 through 75? Or do I have to take more into account?

 

[Paladin]

Viton 90 should work for everything in both stages. 70 is mostly for static seals (non-moving parts). 90 is best for dynamic seals (moving parts).

 

[duckbill]

Okay, taking that thought I re-measured everything latest data in the attachment.

It seems like the Aqua-Lung part number correlates to a possible o-ring size, is there a precedent for this? Or is this how it normally works?

For example: part number 8200-11 has a estimated ID of 6.96mm, measured ID of 8.24mm, and AS568A-011 has a ID of 7.65±0.13. The difference given the stated error is 0.46mm.

Edit: or if we take the estimated ID value of 6.96mm and the error of using AS568A-011 is 0.56mm.

Is that close enough to assume the parts numbers correspond to o-ring sizes?

You got me there. The o-rings we're talking about are measured in American

 

[Paladin]

Well, I just got 250 O-rings of the sizes needed for the Aquarius first stage. I have a friend who is going to punch out a passel of HP seats. It won't be long now and I'll have a lifetime supply of Aquarius parts!

 

[duckbill]

That's the way to do it, Paladin. I eliminated the middlemen years ago and have no regrets. I learned that some things are just better done myself. If I ever do have a problem, I know where I live:devious: