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<DIV><FONT size=3>When you are a half foot below your OP depth, the automatic
OPV knows it and stays shut; when you rise to a half foot above your OP depth,
the OPV valve knows that and opens just long enough to re-equalize the
pressure. It continues to do this as you ascend. Don't latch on to
"half foot" as a standard. I only mean that as an example; it depends on
the cracking pressure chosen. In reality, once the cracking differential
is reached and the valve opens, you'll probably be ascending faster than the OPV
is releasing internal pressure. That is, since the external water pressure
is decreasing as you rise, the differential tends to increase unless the OPV can
keep up with it.</FONT></DIV>
<DIV><FONT size=3></FONT> </DIV>
<DIV><FONT size=3>Hank, you're making a good point for having an adequately
sized OPV.</FONT></DIV>
<DIV><FONT size=3></FONT> </DIV>
<DIV><FONT size=3>Guys, we have two different threads going on the same
topic. Can we merge them?</FONT></DIV>
<DIV><FONT size=3></FONT> </DIV>
<DIV><FONT size=3>Jim</FONT></DIV>
<DIV> </DIV>
<DIV>
<DIV>In a message dated 6/19/2015 3:16:34 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>I don't get the "in the hands" part... its completely
automatic.</DIV>
<DIV class=gmail_extra><BR>
<DIV class=gmail_quote>On Fri, Jun 19, 2015 at 4:09 PM, hank pronk via
Personal_Submersibles <SPAN dir=ltr><<A
title=mailto:personal_submersibles@psubs.org
href="mailto:personal_submersibles@psubs.org"
target=_blank>personal_submersibles@psubs.org</A>></SPAN> wrote:<BR>
<BLOCKQUOTE class=gmail_quote
style="PADDING-LEFT: 1ex; MARGIN: 0px 0px 0px 0.8ex; BORDER-LEFT: #ccc 1px solid"><BR>Agreed,<BR>In
the hands of an experienced submarine operator an over pressure valve is
safe, providing it is large enough. I have not seen an example of a
large enough OPV. A simple valve in the hatch will do the same job,
just need an umbrella :-)<BR>The noise of a compressor is a welcome sound if
it means keeping the dome on the sub
:-)<BR>Hank--------------------------------------------<BR>On Fri, 6/19/15,
Carsten Standfuß" 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] over pressure
valve<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:
Friday, June 19, 2015, 2:47 PM<BR>
<DIV>
<DIV class=h5><BR> But a overpressure vale works<BR> full auto. A
compressor<BR> not. <BR><BR> A OPV needs<BR> no
energy - but a compressor did.<BR><BR><BR> A OPV needs no room -
but<BR> a compressor did.<BR><BR> And a<BR> compressor
is<BR> a noisy
solution..<BR><BR> vbr<BR> Carsten<BR><BR><BR><BR> "hank<BR> pronk
via Personal_Submersibles" <<A
title=mailto:personal_submersibles@psubs.org
href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</A>><BR> schrieb:<BR> >
Personally I think an onboard<BR> compressor is a much safer option
than an over pressure<BR> valve. There are multiple safety
benefits to an onboard<BR> compressor, over pressure being the
biggy. With a<BR> compressor you can get rid of the pressure
without surfacing<BR> and trying to control a perfect ascent.
With the OPV you<BR> have to surface a bit and let air out and wait
then surface<BR> more and wait and so on. You can't just surface and
hope<BR> the valve keeps up with the demand. This is more
important<BR> for subs with large domes.<BR> > The
next<BR> benefit to a compressor is, if you lost all your air,
you<BR> surface by dropping your weight. In my case the weight
is<BR> small and I would also drop the thruster and tail
assembly.<BR> Still, not much sub out of the water. With the
compressor,<BR> I can open my vent valve in the hatch and use the
compressor<BR> to fill the ballast tanks.<BR> >
Hank<BR> ><BR> _______________________________________________<BR> >
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