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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Gents, I think we’re seriously over-complicating this one. The automatic overpressure valves typically have a spring loaded stem. Want a manual valve? All you
do is put your finger on the stem and press a little. You would do that if you wanted to open the valve at less than its cracking pressure, or just for a little ventilation when there is no pressure differential.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">I’m not following the interlock part, because if the valve is automatic then you are always equalized and can’t open the hatch in any other condition. <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">As for installing a compressor just for the purposes of pulling a pre-dive vacuum, in my opinion it has a way too high moving-parts-to-benefit ratio. You can
pull a vacuum at the start of the day, on land or (I wish) on the deck of your support ship. But afloat before every single dive? I’m not aware of anyone doing that. <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Best,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><br>
Alec<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> Personal_Submersibles [mailto:personal_submersibles-bounces@psubs.org]
<b>On Behalf Of </b>jimtoddpsub@aol.com<br>
<b>Sent:</b> Wednesday, December 11, 2013 10:20 AM<br>
<b>To:</b> personal_submersibles@psubs.org<br>
<b>Subject:</b> Re: [PSUBS-MAILIST] G.L. summary Pressure Hull<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><span style="font-family:"Arial","sans-serif";color:black">It seems that the need for sensing could be eliminated (as far as the present question goes) by positioning the handle for the pressure relief valve in such a manner that it would
interfere with releasing the hatch latch unless the relief valve handle was in the open position. In other words, you have to move the handle to out of the way before you can get to the hatch release.
</span><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:black"><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:black"> <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-family:"Arial","sans-serif";color:black">Having a manual control handle doesn't preclude the relief valve from being automatic. It just means the manual portion leading to the auto portion was open. It seems like a good
idea for the manual valve to be opened at some reasonable depth prior to surfacing so any overpressure is free to flow to the auto relief. You don't want overpressure to blow the hatch open when you're still two feet below the surface. If the relief system
is entirely manual, you have to wait until surfaced to open the valve unless the overpressure is particularly high.</span><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:black"><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:black"> <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-family:"Arial","sans-serif";color:black">Jim</span><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:black"><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:black"> <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:black"> <o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:black">-----Original Message-----<br>
From: Joe Perkel <<a href="mailto:josephperkel@yahoo.com">josephperkel@yahoo.com</a>><br>
To: personal_submersibles <<a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>><br>
Sent: Wed, Dec 11, 2013 8:54 am<br>
Subject: Re: [PSUBS-MAILIST] G.L. summary Pressure Hull<o:p></o:p></span></p>
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<p class="MsoNormal">Alan<br>
<br>
No definitive answer but we can postulate that both sensing and actuation are involved.
<br>
<br>
On sensing, differential pressure on either side of the hatch is translated to a impulse to actuation.<br>
<br>
On actuation, a method of locking out the operator from physically un-dogging the hatch, is the only way to meet the standard as per your O.P.<br>
<br>
Joe<a href="http://overview.mail.yahoo.com?.src=iOS" target="_blank"><br>
<br>
Sent from Yahoo Mail for iPad</a><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:9.0pt;font-family:"Arial","sans-serif";color:black">From:
</span></b><span style="font-size:9.0pt;font-family:"Arial","sans-serif";color:black">hank pronk <<a href="mailto:hanker_20032000@yahoo.ca">hanker_20032000@yahoo.ca</a>>;
<br>
<b>To: </b>Personal Submersibles General Discussion <<a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>>;
<br>
<b>Subject: </b>Re: [PSUBS-MAILIST] G.L. summary Pressure Hull <br>
<b>Sent: </b>Wed, Dec 11, 2013 2:36:26 PM <o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-family:"Helvetica","sans-serif";color:black">Alan,<o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-family:"Helvetica","sans-serif";color:black">Is this equalization from overpressure inside the hull? or external pressure. <o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-family:"Helvetica","sans-serif";color:black">Hank <o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt;background:white"><span style="font-family:"Helvetica","sans-serif";color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:black">On Wednesday, December 11, 2013 1:23:21 AM, Alan <<a href="mailto:alanlindsayjames@yahoo.com">alanlindsayjames@yahoo.com</a>> wrote:</span><span style="font-family:"Helvetica","sans-serif";color:black"><o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-family:"Helvetica","sans-serif";color:black">Can anyone enlighten me on what sought of mechanism<o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-family:"Helvetica","sans-serif";color:black">is used that renders the opening of the hatch possible only after<o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-family:"Helvetica","sans-serif";color:black">equalisation, as per G.L. Requirements?<o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-family:"Helvetica","sans-serif";color:black">Thanks<o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-family:"Helvetica","sans-serif";color:black">Alan<br>
<br>
Sent from my iPad<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt;background:white"><span style="font-family:"Helvetica","sans-serif";color:black"><br>
On 11/12/2013, at 3:01 PM, Alan James <<a href="mailto:alanlindsayjames@yahoo.com">alanlindsayjames@yahoo.com</a>> wrote:<o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:14.0pt;font-family:"Helvetica","sans-serif";color:black">Hi,<o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:14.0pt;font-family:"Helvetica","sans-serif";color:black">I'm not covering much in this section because if I started on construction<o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:14.0pt;font-family:"Helvetica","sans-serif";color:black">regulations, I would just be duplicating what was printed.<o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:14.0pt;font-family:"Helvetica","sans-serif";color:black">G.L. wants you to have manufacturer certificates for every non structural screw.<o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:14.0pt;font-family:"Helvetica","sans-serif";color:black">Any company you contract to do your welding has to have their facilities, personal<o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:14.0pt;font-family:"Helvetica","sans-serif";color:black">& supervision approved by G.L..<o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:14.0pt;font-family:"Helvetica","sans-serif";color:black">Some points of interest are.... hatches need to be opened from both sides, they need<o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:14.0pt;font-family:"Helvetica","sans-serif";color:black">to be able to be secured open, they need to be designed in a way that opening of the<o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:14.0pt;font-family:"Helvetica","sans-serif";color:black">hatch is only possible after equalization. Two measures are required to guarantee that<o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:14.0pt;font-family:"Helvetica","sans-serif";color:black">the hatches are closed & secured before diving; one measure is to be visibly noticeable.<o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:14.0pt;font-family:"Helvetica","sans-serif";color:black">Mechanical measures for stopping a banging of the hatch is required.<o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:14.0pt;font-family:"Helvetica","sans-serif";color:black">Any external through hulls are to be protected against damage by appendages or covers.<o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:14.0pt;font-family:"Helvetica","sans-serif";color:black">If you are doing calculations on a computer you have to prove that the program is suitable.<o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:14.0pt;font-family:"Helvetica","sans-serif";color:black">Alan<o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-family:"Helvetica","sans-serif";color:black">_______________________________________________<br>
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<p class="MsoNormal" style="background:white"><span style="font-family:"Helvetica","sans-serif";color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-family:"Helvetica","sans-serif";color:black">_______________________________________________<br>
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<pre style="background:white"><tt><span style="color:black">_______________________________________________<o:p></o:p></span></tt></pre>
<pre style="background:white"><tt><span style="color:black">Personal_Submersibles mailing list<o:p></o:p></span></tt></pre>
<pre style="background:white"><tt><span style="color:black"><a href="mailto:Personal_Submersibles@psubs.org">Personal_Submersibles@psubs.org</a><o:p></o:p></span></tt></pre>
<pre style="background:white"><tt><span style="color:black"><a href="http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles" target="_blank">http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles</a><o:p></o:p></span></tt></pre>
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