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There is a bevel and O-ring on the outer edge of the conical frustum viewport on the K-350 hatch design. I was just looking at a flat disk sealing arrangement in Stachiw's book on page 1043 that has a outer O-ring in the bevel of the window, and then a soft gasket covering that and the outer surface being pressed on by the retaining ring. That said gasket is not for sealing so much as it is to make a soft even contact between the acrylic and it's retaining ring. Also look at pages 1041 and 1042. On page 412 you can see a O-ring groove being applied in the vertical side wall of a viewport seating ring, as well as two gaskets. This configuration can take both internal and external pressure. One could make a flat disk viewport assembly like this, with out the O-ring and it's gland for are basic external pressure viewports. This way you have a double seal, and a soft contact between the retaining ring and the acrylic, and no need to bevel the acrylic. That's KISS, right? Simplicity if largely based on the mind looking at it. Regards, Szybowski From: ojaivalleybeefarm@dslextreme.com To: personal_submersibles@psubs.org Subject: RE: [PSUBS-MAILIST] Double Seal Requirements of PVHO Certified Viewports Date: Fri, 24 Jul 2009 08:50:10 -0700 Hi Frank, I
couldn't seem to find that picture on psubs ( what happened to all the misc.
pictures?) But really it's only two seals, there is no gasket on the
retaining ring.
Brian
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