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<DIV><FONT size=3>If the pressure differential exceeds the preset cracking
pressure, the valve will open on its own to relieve the excess pressure.
If the pressure differential is less than the cracking pressure, it would have
to be opened manually. If the differential were only slightly greater than
the preset cracking pressure, I suppose opening it manually would open
it wider for more rapid equalization on many types of valves.</FONT></DIV>
<DIV><FONT size=3>Jim</FONT></DIV>
<DIV> </DIV>
<DIV>
<DIV>In a message dated 6/18/2015 2:40:58 P.M. Central Daylight Time,
personal_submersibles@psubs.org writes:</DIV>
<BLOCKQUOTE
style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: blue 2px solid"><FONT
style="BACKGROUND-COLOR: transparent" color=#000000 size=2 face=Arial>
<DIV style="FONT-SIZE: 10pt; FONT-FAMILY: Arial, sans-serif">
<DIV>Jim,</DIV>
<DIV> In that case
is it necessary to bump the sealed check valve to make it open?</DIV>
<DIV> </DIV>
<DIV> </DIV>
<DIV>Alec, I guess what I meant to say was if the check valve is left in
an open line to the outside all the time, rather than being isolated by
another valve.</DIV>
<DIV> </DIV>
<DIV>Brian <BR><BR>--- personal_submersibles@psubs.org
wrote:<BR><BR>From: via Personal_Submersibles
<personal_submersibles@psubs.org><BR>To:
personal_submersibles@psubs.org<BR>Subject: Re: [PSUBS-MAILIST]
Idea..?<BR>Date: Thu, 18 Jun 2015 14:53:15 -0400<BR><BR></DIV><FONT
color=#000000 size=2 face=Arial>
<DIV></DIV>
<DIV><FONT size=3>Brian, it also has to do with cracking pressure. When
you surface the sub might be slightly over pressure but not with enough
differential to open the valve automatically. That's when you open it
manually. That would also equalize pressure if you have negative
pressure in the sub to make it a whole lot easier to open the
hatch.</FONT></DIV>
<DIV><FONT size=3>Jim </FONT></DIV>
<DIV> </DIV>
<DIV>
<DIV>In a message dated 6/18/2015 1:40:32 P.M. Central Daylight Time,
personal_submersibles@psubs.org writes:</DIV>
<BLOCKQUOTE
style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: blue 2px solid"><FONT
style="BACKGROUND-COLOR: transparent" color=#000000 size=2 face=Arial>
<DIV dir=ltr>It is nothing but a T shape sealed by a spring. If internal
pressure builds up, it pushes the spring and the valve opens. So it is a
normally closed valve... but I suppose you could say its "open all the time"
in the sense that anytime pressure builds up, it will open.</DIV>
<DIV><BR>
<DIV>On Thu, Jun 18, 2015 at 2:35 PM, Brian Cox via Personal_Submersibles
<SPAN dir=ltr><<A title=mailto:personal_submersibles@psubs.org
href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</A>></SPAN>
wrote:<BR>
<BLOCKQUOTE
style="PADDING-LEFT: 1ex; MARGIN: 0px 0px 0px 0.8ex; BORDER-LEFT: rgb(204,204,204) 1px solid">
<DIV style="FONT-SIZE: 10pt; FONT-FAMILY: Arial,sans-serif">
<DIV>Couldn't you, theoretically, have that valve open to the
outside all the time? </DIV>
<DIV> </DIV>
<DIV><SPAN>Brian <BR><BR>--- <A
title=mailto:personal_submersibles@psubs.org
href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</A>
wrote:<BR><BR>From: Alec Smyth via Personal_Submersibles <<A
title=mailto:personal_submersibles@psubs.org
href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</A>><BR>To:
Personal Submersibles General Discussion <<A
title=mailto:personal_submersibles@psubs.org
href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</A>><BR>Subject:
Re: [PSUBS-MAILIST] Idea..?<BR></SPAN>Date: Thu, 18 Jun 2015 12:15:57
-0400<BR><BR></DIV>
<DIV>
<DIV>
<DIV dir=ltr>I think most have an OP valve, and I'd strongly encourage any
who don't to put one in. If you read Kittredge's book, the lack of an OP
valve was the cause of the only K-boat accident so far. Fortunately
nothing happened to him, but Kittredge had a slow cabin air leak during
his dive and upon surfacing blew out the dome when just below the surface.
He was blown out himself with it. The sub sank, and he proceeded to
re-float it without losing beat. I use the OP valve routinely to
equalize pressure so I can open the hatch easily. Just a little push on
the stem does it. One thing about OP valves, they have to be capable of
handling large flow rates. Don't use a little Swagelok check valve or such
small thing.
<DIV><BR></DIV>
<DIV>Best,<BR><BR>Alec<BR>
<DIV><BR></DIV>
<DIV><BR></DIV></DIV></DIV>
<DIV><BR>
<DIV>On Thu, Jun 18, 2015 at 10:55 AM, Brian Cox via Personal_Submersibles
<SPAN dir=ltr><<A title=mailto:personal_submersibles@psubs.org
href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</A>></SPAN>
wrote:<BR>
<BLOCKQUOTE
style="PADDING-LEFT: 1ex; MARGIN: 0px 0px 0px 0.8ex; BORDER-LEFT: rgb(204,204,204) 1px solid">Also
Alec, I noticed your check valve overpressure valve in the
photo section. That seems like a great solution to the
problem! I guess I was not aware of that, does everybody
have one of those?<BR><BR><BR>Brian<BR><BR>--- <A
title=mailto:personal_submersibles@psubs.org
href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</A>
wrote:<BR><BR>From: hank pronk via Personal_Submersibles <<A
title=mailto:personal_submersibles@psubs.org
href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</A>><BR><SPAN>To:
Personal Submersibles General Discussion <<A
title=mailto:personal_submersibles@psubs.org
href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</A>><BR>Subject:
Re: [PSUBS-MAILIST] Idea..?<BR></SPAN>Date: Thu, 18 Jun 2015 05:25:30
-0700<BR>
<DIV>
<DIV><BR><BR>personally, I always avoid welding a machined part to the
hull. I weld a flange or nipple to the hull then bolt or thread
the machined part to that. This is my solution to a lack of
tooling and expertise.<BR>Hank
--------------------------------------------<BR>On Thu, 6/18/15, James
Frankland via Personal_Submersibles <<A
title=mailto:personal_submersibles@psubs.org
href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</A>>
wrote:<BR><BR> Subject: Re: [PSUBS-MAILIST] Idea..?<BR> To:
"Personal Submersibles General Discussion" <<A
title=mailto:personal_submersibles@psubs.org
href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</A>><BR> Received:
Thursday, June 18, 2015, 4:58
AM<BR><BR> Hi<BR> Alec\Brian, Yes, maybe it
would<BR> push in. A flat step would probably be better like
you<BR> say. But maybe im over thinking it as usual.
Probably<BR> not required. Brian, I used the<BR> 5\8ths
bar because that's what was specified on the<BR> plans.
However, its also convenient for using a 16mm<BR> reamer for the
bore. <BR> regardsJames <BR> On 18 June 2015
at 03:04,<BR> Brian Cox via Personal_Submersibles <<A
title=mailto:personal_submersibles@psubs.org
href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</A>><BR> wrote:<BR> Oh
cool ! Thanks Alec<BR> ! I owe you
much over the years<BR> ! Brian<BR> --- <A
title=mailto:personal_submersibles@psubs.org
href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</A><BR> wrote:<BR><BR> From:
Alec Smyth via<BR> Personal_Submersibles <<A
title=mailto:personal_submersibles@psubs.org
href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</A>><BR> To:
Personal Submersibles General Discussion<BR> <<A
title=mailto:personal_submersibles@psubs.org
href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</A>><BR> Subject:
Re: [PSUBS-MAILIST] Idea..?<BR> Date: Wed, 17 Jun 2015 16:40:56
-0400<BR><BR> Hi Brian,<BR> I tend to use quite
thick<BR> through-hulls because its easier for me to machine
the<BR> O-ring grooves into the shaft than into the insert. In
my<BR> case its just a matter of the tooling I have on hand. If
you<BR> have the tooling to put the grooves in the insert, half
an<BR> inch is fine for many
applications.<BR> Best,<BR><BR> Alec <BR> On<BR> Wed,
Jun 17, 2015 at 3:22 PM, Brian Cox via<BR> Personal_Submersibles
<<A title=mailto:personal_submersibles@psubs.org
href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</A>><BR> wrote:<BR> Alec,
James, I'm<BR> using mostly 1/2" stainless rod through-out
for most<BR> all of my hull penetrations ( for valves and
flaps) , I<BR> noticed in the example it was a 5/8" rod,
Why such a<BR> heavy duty thickness? Was that for a
particular<BR> function? Brian<BR><BR> --- <A
title=mailto:personal_submersibles@psubs.org
href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</A><BR> wrote:<BR><BR> From:
Alec Smyth via<BR> Personal_Submersibles <<A
title=mailto:personal_submersibles@psubs.org
href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</A>><BR> To:
Personal Submersibles General Discussion<BR> <<A
title=mailto:personal_submersibles@psubs.org
href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</A>><BR> Subject:
Re: [PSUBS-MAILIST] Idea..?<BR> Date: Wed, 17 Jun 2015 14:03:17
-0400<BR><BR> Hi James,<BR> I think<BR> with the taper,
this would tend to push in and jam. The idea<BR> is neat, however,
and would probably work fine with a step<BR> instead of a taper. On
the other hand, does an O ring sealed<BR> through-hull ever fail
catastrophically? I've had the<BR> odd drip, but that's all I've
bad as
I've<BR> seen.<BR> Best,<BR> Alec<BR> On<BR> Wed,
Jun 17, 2015 at 12:26 PM, James Frankland
via<BR> Personal_Submersibles <<A
title=mailto:personal_submersibles@psubs.org
href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</A>><BR> wrote:<BR> Hi
All Seeing as its a<BR> bit quite I thought I would show this
idea. Its super<BR> simple.... I have been thinking
how<BR> you could stop a leaking through hull. Thinking of K
boat<BR> type 5\8th through hulls as in the<BR> plans. I
believe Scott had a leak<BR> when he did his deep test due to a
faulty O ring?<BR><BR> Anyway, here is my idea.
It<BR> would take a little bit more machining, but not
much. <BR> Machine the 5\8ths bar with a taper on the
protruding<BR> part and a taper on the top to help push the bar
through. <BR> (I did that on mine anyway). The handle is
made with a cam<BR> type end. <BR><BR> If you get
a<BR> leak, you can pull the handle up. The bar would be
pulled<BR> up, forcing the taper to jam into the penetrator,
hopefully<BR> stopping most of the leak. I suppose you could
even<BR> machine a matching taper into the start of the through
hull<BR> to match? I suppose the bar could get<BR> pushed
through and jam on its own. That's
a<BR> possibility. Pic<BR> attached. Kind<BR> RegardsJames <BR> <BR><BR> _______________________________________________<BR><BR> Personal_Submersibles
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