It says that the mating surface for the window (conical frustrum) can be considered as one seal. Perry O-rings (after this change was made for PVHO) had the corner machined off at the outer rim of the port and a matching groove cut into the reinforcing ring. The retaining ring served as a top for what would then be a square O-ring groove.
Vance
-----Original Message-----
From: ShellyDalg@aol.com
To: personal_submersibles@psubs.org
Sent: Fri, Jul 24, 2009 10:23 am
Subject: Re: [PSUBS-MAILIST] Double Seal Requirements of PVHO Certified Viewports
Section 3 says the "gasket under the retaining ring" is one of the seals. The sikaflex or O ring or flange gasket is the other.
It says no O ring groove in the window or seat, so where would you put it? In the side of the mounting ring?