<html><head></head><body><p dir="ltr">Is it possible that this rule is simply another way of stating that hatches need be designed to seal with pressure, such that they physically cannot be opened unless equalized (+/- a person's strength)? Dogs in that case are just a means of providing a little bit of precompression on the O-ring in the absence of a pressure differential, and to hold the hatch against _slight_ reverse pressure, such at the 1 ATM specified by ABS.</p>
<p dir="ltr">ABS' version says that a means must be provided to equalize pressure before opening (needle valve?), that means must be provided to determine the pressure on either side, and that interlocks must be present to prevent e.g. submerging with open hatches.</p>
<p dir="ltr">I wonder if GL is really that prescriptive, or if we're misinterpreting?</p>
<p dir="ltr">Sean<br>
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<br><br><div class="gmail_quote">Joe Perkel <josephperkel@yahoo.com> wrote:<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<table cellspacing="0" cellpadding="0" border="0"><tbody><tr><td valign="top">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"><br /><br />Sent from Yahoo Mail for iPad</a></td></tr></tbody></table> <div id="_origMsg_">
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<span style="font-weight:bold">From:</span>
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hank pronk <hanker_20032000@yahoo.ca>; <br />
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Personal Submersibles General Discussion <personal_submersibles@psubs.org>; <br />
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<span style="font-weight:bold">Subject:</span>
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Re: [PSUBS-MAILIST] G.L. summary Pressure Hull <br />
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<span style="font-weight:bold">Sent:</span>
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Wed, Dec 11, 2013 2:36:26 PM <br />
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<table cellspacing="0" cellpadding="0" border="0"><tbody><tr><td valign="top"><div style="color:#000;background-color:#fff;font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:12pt;"><div><span>Alan,</span></div><div><span>Is this equalization from overpressure inside the hull? or external pressure. </span></div><div><span>Hank </span></div><div class="yahoo_quoted" style="display:block;"> <br clear="none" /> <br clear="none" /> <div style="font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:12pt;"> <div style="font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:12pt;"> <div class="yqt1385517701" id="yqt07881"><div dir="ltr"> <font face="Arial" size="2"> On Wednesday, December 11, 2013 1:23:21 AM, Alan <alanlindsayjames@yahoo.com> wrote:<br clear="none" /> </font> </div> <div class="y_msg_container"><div
id="yiv6100496818"><div><div>Can
anyone enlighten me on what sought of mechanism</div><div>is used that renders the opening of the
hatch possible only after</div><div>equalisation, as per G.L. Requirements?</div><div>Thanks</div><div>Alan<br clear="none" /><br clear="none" />Sent from my iPad</div><div class="yiv6100496818yqt6118645076" id="yiv6100496818yqt49514"><div><br clear="none" />On 11/12/2013, at 3:01 PM, Alan James <<a rel="nofollow" shape="rect" ymailto="mailto:alanlindsayjames@yahoo.com" target="_blank" href="javascript:return">alanlindsayjames@yahoo.com</a>> wrote:<br clear="none" /><br clear="none" /></div><blockquote type="cite"><div><div style="color:rgb(0, 0, 0);font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:14pt;background-color:rgb(255, 255, 255);"><div>Hi,</div><div>I'm not covering much in this section because if I started on construction</div><div>regulations, I would just be duplicating what was printed.</div><div>G.L. wants you to have manufacturer certificates for every non structural
screw.</div><div>Any company you contract to do your welding has to have their facilities, personal</div><div>& supervision approved by G.L..</div><div>Some points of interest are.... hatches need to be opened from both sides, they need</div><div>to be able to be secured open, they need to be designed in a way that opening of the</div><div>hatch is only possible after equalization. Two measures are required to guarantee that</div><div>the hatches are closed & secured before diving; one measure is to be visibly noticeable.</div><div>Mechanical
measures for stopping a banging of the hatch is required.</div><div>Any external through hulls are to be protected against damage by appendages or covers.</div><div>If you are doing calculations on a computer you have to prove that the program is suitable.</div><div>Alan</div></div></div></blockquote></div><blockquote type="cite"><div><span>_______________________________________________</span><br clear="none" /><span>Personal_Submersibles mailing list</span><br clear="none" /><span><a rel="nofollow" shape="rect" ymailto="mailto:Personal_Submersibles@psubs.org" target="_blank" href="javascript:return">Personal_Submersibles@psubs.org</a></span><br clear="none" /><span><a rel="nofollow" shape="rect" target="_blank" href="http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles">http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles</a></span><br clear="none" /></div></blockquote></div></div><br clear="none" /><div class="yqt6118645076"
id="yqt62748">_______________________________________________<br clear="none" />Personal_Submersibles mailing list<br clear="none" /><a rel="nofollow" shape="rect" ymailto="mailto:Personal_Submersibles@psubs.org" target="_blank" href="javascript:return">Personal_Submersibles@psubs.org</a><br clear="none" /><a rel="nofollow" shape="rect" target="_blank" href="http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles">http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles</a><br clear="none" /></div><br clear="none" /><br clear="none" /></div></div> </div> </div> </div> </div></td></tr></tbody></table>
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