so it snaps in and stays there.
Dan H.
----- Original Message -----
From: <james@guernseysubmarine.com>
To: <personal_submersibles@psubs.org>
Sent: Friday, February 22, 2008 3:53 AM
Subject: RE: [PSUBS-MAILIST] Coved O-ring Groove
Hi Brent.
I like the snow cave! Looks like that bit in "Alien" when they go
troopsing off to find the space ship. I'm sure your on another planet!
Anyway, about the hatch groove.
Not to long ago Frank D. asked about whether he should cut a coved or
square O-ring groove in his hatch, and I don't remember if any one
answered > him?
I just had mine machined at a professional shop 2 days ago. The Kittredge
plans show a square groove with a 10 degree angle on the inside diameter.
I assume this angle is to allow somewhere for the o ring to compress into.
Anyway, thats how i've done it, right or wrong. You can see it here.
http://www.guernseysubmarine.com/index_files/Page9271.htm
James
----- Original Message -----
From: Brian Cox [mailto:ojaivalleybeefarm@dslextreme.com]
To: personal_submersibles@psubs.org
Sent: Thu, 21 Feb 2008 23:38:45 -0800
Subject: RE: [PSUBS-MAILIST] Coved O-ring Groove
Wouldn't the hatch be metal to metal and the pressure coming in at the
hatch/seat division make the o ring try to extruded into the sub. The
pressure that the o ring would extrude would be very high, higher than the
collapse pressure of the sub I would think.
Brian
-----Original Message-----
From: owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org]On Behalf Of Brent Hartwig
Sent: Thursday, February 21, 2008 9:37 PM
To: personal_submersibles@psubs.org
Subject: RE: [PSUBS-MAILIST] Coved O-ring Groove
I worked up three more drawings to show what I was thinking a O-ring in a
coved gland or square gland with silicone or urethane filling the square
corners of the gland, would look like being under great pressure. Since I
think there would be far more pressure coming down on the O-ring from the
hydrostatic pressure on the hatch's outer surface then would be coming in
from the space between the hatch flange and seat. Also I would expect that
the more exterior hydrostatic pressure is applied to the hatch that it
would
further help seal the O-ring against the seating surface, keeping it from
extruding to the low pressure side of the seal. Any thoughts?
http://www.frappr.com/?a=viewphoto&id=4001713&pid=9275457
Regards,
Brent Hartwig
----------------------------------------------------------------------------
From: brenthartwig@hotmail.com
To: personal_submersibles@psubs.org
Subject: [PSUBS-MAILIST] Bottomed Out Hatch Flange O-ring Failure
Date: Sat, 2 Feb 2008 15:37:06 -0800
I've been thinking about this for some time now, and thought it was
time
to talk about it. There has been a fair bit of discussion on O-ring
failure
in a hatch, by means of extrusion. I don't think this would be the mode of
failure for a hatch O-ring, and here is why. When the hatch is shut and
under water, the exposed surface area on the O-ring between the two metal
mating surfaces is vastly smaller then the surface area on the top of the
whole hatch pushing down on it. This means that if the pressure is to
great
for the O-ring, the hatch mating surfaces will bottom out and then the
water
will just start to flow past the O-ring without extruding it. Also if the
hatch bottoms out there will be no place for the O-ring to extrude into.
At
this point I think the O-ring would just rather let the water pass between
it and the flat flange mating surface, rather then extrude. Any thoughts?
I made up a model to better show what I'm thinking the O-ring would
look
like when fully compressed into it's gland by a bottomed out hatch flange.
http://www.frappr.com/?a=viewphoto&id=4001713&pid=9115314
Here is a really great link I found today showing a lot more modes of
O-ring failure then I'd seen any place else.
http://www.allorings.com/failure.htm
Not to long ago Frank D. asked about whether he should cut a coved or
square O-ring groove in his hatch, and I don't remember if any one
answered
him? I would think the cove would make for less room for a O-ring to
deform
into to help keep the metal hatch surfaces from bottoming out. While
watching the Nova show on the Alicia sub called "Underwater Dream
Machine",
I noticed that they put a lot of silicone type sealant in the O-ring
groove
that is in the large unboltable flange, that keeps the two large steel
pressure hull sections together. I'm guessing they did this to fill the
extra space of a square type O-ring groove, that the O-ring doesn't fill
when in a non compressed state. So there will be more space between the
flanges at depth, to keep them from bottoming out. Any thoughts, or should
I
add more O2 to my snow cave?
Here are two pictures showing snow through the windows of my house. One
shows snow up against a window in the the spa room, and the other shows
that
the snow outside my shop window is completely blocking the view out the
window. So when I say snow cave, I mean it. This is not normal for around
here.
http://www.frappr.com/?a=viewphoto&id=4001713&pid=9115443
Regards,
Brent Hartwig
************************************************************************
************************************************************************
************************************************************************
The personal submersibles mailing list complies with the US Federal
CAN-SPAM Act of 2003. Your email address appears in our database
because either you, or someone you know, requested you receive messages
from our organization.
If you want to be removed from this mailing list simply click on the
link below or send a blank email message to:
removeme-personal_submersibles@psubs.org
Removal of your email address from this mailing list occurs by an
automated process and should be complete within five minutes of
our server receiving your request.
PSUBS.ORG
PO Box 53
Weare, NH 03281
603-529-1100
************************************************************************
************************************************************************
************************************************************************