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Oh Frank, I forgot to mention that the drawing you saw that I did of the hatch that went metal to metal and the angle cut on the exterior groove wall. I didn't brake the sharp corners, as I should have. But on the other hand, my groove surfaces were perfectly smooth. ;} " Personally I'm always ready to learn, although I do not always like being taught. " ~ Sir Winston Churchill Regards, Szybowski From: ShellyDalg@aol.com Date: Mon, 7 Sep 2009 18:18:31 -0400 Subject: Re: [PSUBS-MAILIST] No Machining Hatch Sealing Concept To: personal_submersibles@psubs.org Hey Brent. Keep thinking, dreamers are good.
Still, you're beating a dead horse. I can see where the welded ring thing may be cheaper/easier on a big square door for a hyperbaric chamber but for a round sub hatch.....the $300 machinist's bill was a no brainer.
Another note about the hatch groove as mentioned by Hugh, the bottom of the groove needs a little radius there so that when the pressure gets really high and the "O" ring is deformed into a slightly rectangular shape, a sharp corner at the groove bottom will damage the "O" ring. I got this from the salesman at Parker when I was getting all the info to do my hatch.
The surface of the groove and matching land needs to be as smooth as possible too. The Parker book has a LOT of good info there. Well worth a read.
On the "purchase" of the "O" ring......I was directed to an authorized dealer and ended up paying $75 for 2 "O" rings. They really wanted me to buy 200 of them. Much better to get them from Mcmaster-Carr.
I will possibly get a dove tail added to the groove later and get new "O" rigs just slightly smaller so they stretch into place. As several guys have said, there's a "stretch" factor to be considered and a "squeeze" factor too. All that info is in the Parker book. Frank D.
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