Scott Minton wrote:
>
> Steve,
>
> I am running headers. I was aware of the motorsport
> piece but didn't think it would clear the headers.
> Guess I was right. I think I do have an original
> remote fitting. However it does have an oring just
> below the hex head. There is even a groove for the
> ring. If its not supposed to be an O ring, then what?
> Possibly a fiber gasket under the hex?
>
> Scott
Scott,
No, the original Tiger fitting was cast iron, and had fiber fittings.
The remote adapters usually are aluminum and have O-rings.
I have seen many "o-ring seal" designs, in the automotive after market,
that use a round cut groove for the o-ring seat. Somehow they believe
this to be appropriate.
It is not correct, and not in accordance with SAE or aircraft/aerospace
design criteria. A proper o-ring seal is between two flat surfaces. One
is genuinely flat, and the other is a very specific square cross
section. Not round. The o-ring is squeezed by the opposing flat surfaces
of the top and the bottom of the grooved portion. This causes the o-ring
to expand against the right angled side-wall and the seal is made there.
Increases in internal pressure cause the o-ring to press even harder
against these surfaces, making the seal even better at higher pressures.
The o-rings themselves are of a specific thickness, material, hardness,
and diameter for the application. We have used O-rings over 12 feet in
diameter to seal 6.000 deg.. F. gases at 1,000 psia from leaking out of
a joint in a rocket engine, without ever having a failure in 1200 hot
firing seals on one program alone.
The only failure you have ever heard about was from a design that was
operated at an ambient temperature too cold for the o-ring to have the
proper resilience to seal the moving gap quickly enough. Their solution
was a joint re-design, to increase o-ring compression with vessel
expansion, and multiple o-ring seals. Ours already sealed harder with
expansion/rotation and only used 1 o-ring. This is not a criticism of
the original design, as the system that failed was used outside the
temperature design limitations, and the users knew it. It was redesigned
using a "belts, suspenders, and super glue" approach due to the human
risk factor.
Look at your o-ring groove. If it is round, it was NOT designed by
someone with seal knowledge, and the unit should be discarded. A liquid
seal at 100 psia (maximum) and 400 deg.. F. (maximum) should not leak.
These are minor sealing issues with well known professional and
published design criteria.
If this sounds a little harsh, it is only a reminder that not all
automotive after market products are designed by knowledgeable
engineering professionals, and it shows.
Hope you are not sorry you asked, but this particular subject involved
me, professionally, for over 2 years.
--
Steve Laifman < Find out what is most >
B9472289 < important in your life >
< and don't let it get away!>
<SLaifman@SoCal.RR.com>
<http://www.TigersUnited.com/gallery/SteveLaifman.asp>
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