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Brent,
Double O-rings in a design can sometimes actually be a
problem. It's possible to get pressurized fluid, or gas, trapped between
the two O rings. Especially in high pressure dynamic sealing situations,
it's always best to use a single good seal rather then two Ok ones. If one
seal weeps and pressure gets trapped between the two seals, it binds the other
wise free moving shaft even when the external pressure is removed.
In a sub the pressures aren't high and the added safety is
a plus, so their commonly used for shafts.
Dan H.
----- Original Message -----
Sent: Wednesday, August 08, 2007 10:39
PM
Subject: Re: [PSUBS-MAILIST] Double
O-Ring On A Hatch
Brent,
I concur with Vance, Carsten and Peter ..., a single
o-ring witht the correct hardness is the way to go. See
technical note http://www.satoriseal.com/Technical/introduction_to_o-rings.htm on
how o-ring is design to move within it's machined grove under pressure to
seal. Hatch upper and lower faces need land face to
face. If you are designing a hatch, pick a
standard size so that you do not have to introduce a splice.
Cliff
Great works are performed not by strength but by
perseverance. Samuel Johnson
-----
Original Message ---- From: Brent Hartwig
<brenthartwig@hotmail.com> To: PSUBSorg
<personal_submersibles@psubs.org> Sent: Tuesday, August 7, 2007
11:31:47 PM Subject: [PSUBS-MAILIST] Double O-Ring On A Hatch
I finally found a double o-ring on a sub hatch. The sub
on ebay right now called the Great Lake's Submarine mentioned earlier, has
one. Here is the picture. http://www.frappr.com/?a=viewphoto&id=4001713&pid=7375620
Regards,
Brent
Hartwig
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