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<DIV><FONT size=3>Hi Hank,</FONT></DIV>
<DIV><FONT size=3></FONT> </DIV>
<DIV><FONT size=3>See if you agree with my line of thinking: At a
hatch depth of 20 feet you'll have about 9 psi differential on your hatch and
your other penetrations as well. At a hatch depth of 1 foot you have
about .445 psi differential.</FONT></DIV>
<DIV><FONT size=3></FONT> </DIV>
<DIV><FONT size=3>For many things, the greater the pressure differential, the
greater the chance of a leak or seepage. However on the hatch in
particular (and possibly on some other things), the greater the
pressure forcing the hatch against the landing, the more tightly it will
seal. So the hatch might seal well at depth, but leak when barely
submerged</FONT></DIV>
<DIV><FONT size=3></FONT> </DIV>
<DIV><FONT size=3>It seems it would be good to do both a high vacuum and
a low vacuum test. If the hatch seals well at high vacuum, but leaks
down at low vacuum, more work is needed on the latches or the mating
surfaces.</FONT></DIV>
<DIV><FONT size=3></FONT> </DIV>
<DIV><FONT size=3>Best regards,</FONT></DIV>
<DIV><FONT size=3>Jim</FONT></DIV>
<DIV> </DIV>
<DIV>
<DIV>In a message dated 9/2/2013 9:21:58 A.M. Central Daylight Time,
hanker_20032000@yahoo.ca writes:</DIV>
<BLOCKQUOTE
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<DIV style="RIGHT: auto"><SPAN style="RIGHT: auto">Hi James,</SPAN></DIV>
<DIV
style="FONT-SIZE: 16px; FONT-FAMILY: tahoma, new york, times, serif; RIGHT: auto; COLOR: rgb(0,0,0); FONT-STYLE: normal; BACKGROUND-COLOR: transparent"><SPAN
style="RIGHT: auto">I always do a vacuum test before my test dives. I
use a compressor as a vacuum pump and draw out as much air as possible.
Then I have a valve on the hull and a vacuum gauge. I let it sit for 24
hr. If it holds the vacuum your set. </SPAN></DIV>
<DIV
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style="RIGHT: auto">Hank<VAR id=yui-ie-cursor></VAR></SPAN></DIV>
<DIV style="RIGHT: auto"><BR style="RIGHT: auto"></DIV>
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readonly="true"></DIV><FONT size=2 face=Arial><B><SPAN
style="FONT-WEIGHT: bold">From:</SPAN></B> James Frankland
<jamesf@guernseysubmarine.com><BR><B><SPAN
style="FONT-WEIGHT: bold">To:</SPAN></B> personal_submersibles@psubs.org
<BR><B><SPAN style="FONT-WEIGHT: bold">Sent:</SPAN></B> Monday, September 2,
2013 3:45:27 AM<BR><B><SPAN style="FONT-WEIGHT: bold">Subject:</SPAN></B>
[PSUBS-MAILIST] Leak, pressure and life support test<BR></FONT></DIV>
<DIV class=y_msg_container style="RIGHT: auto"><BR>
<DIV id=yiv1016670701 style="RIGHT: auto">
<DIV>Hi All,</DIV>
<DIV> </DIV>
<DIV>I did some tests at the weekend. Very small pics attached as i
havent updated my site yet.</DIV>
<DIV style="RIGHT: auto"> </DIV>
<DIV style="RIGHT: auto">First i tested the battery pods and seals with old
inner tubes. Managed to pump them to about 5psi. Not much but i
think it was ok to indicate any leaks. I couldnt see or hear anything
and pressure remained steady.</DIV>
<DIV> </DIV>
<DIV>Then i did the very sophisticated "saucepan test" over the hatch
viewport. I was just a bit suspicious of this one as it has no gasket,
the lense seats directly to the face. No leak, but agreed, not much test
pressure although the saucepan was full despite the spillage out the
sides.</DIV>
<DIV> </DIV>
<DIV>Next i did a life support test. I filled and ran the scrubber and
then sat inside for an hour with the hatch sealed. CO2 seemed to level
out at about 5500ppm and i topped up O2 when it got to
19%. </DIV>
<DIV> </DIV>
<DIV>i also dropped half a psi of internal pressure and that seemed to hold,
so i am hoping the boat is tight.</DIV>
<DIV> </DIV>
<DIV>I was going to do a leak test in a local fresh water resovoir, but
as im a bit more confident its not going to leak now and its such a logistical
fuss, im going to go straight in the sea. Next week.</DIV>
<DIV>Kind Regards</DIV>
<DIV>James</DIV>
<DIV> </DIV></DIV><BR>_______________________________________________<BR>Personal_Submersibles
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