<html><head></head><body><div style="color:#000; background-color:#fff; font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:16px"><div id="yui_3_16_0_1_1456619427414_9802"><span>Brian,</span></div><div dir="ltr" id="yui_3_16_0_1_1456619427414_9804"><span id="yui_3_16_0_1_1456619427414_9803">one way round that would be to weld a tube to the port below the</span></div><div dir="ltr" id="yui_3_16_0_1_1456619427414_9805"><span id="yui_3_16_0_1_1456619427414_9806">water line & have the tube coming up to the top of the sub with the exhaust valve</span></div><div dir="ltr" id="yui_3_16_0_1_1456619427414_9805"><span>mounted on that. However it would be difficult to set up a mechanism to plunge</span></div><div dir="ltr" id="yui_3_16_0_1_1456619427414_9805"><span>it.</span></div><div dir="ltr" id="yui_3_16_0_1_1456619427414_9805"><span>Alan</span></div><div class="qtdSeparateBR" id="yui_3_16_0_1_1456619427414_9881"><br><br></div><div class="yahoo_quoted" id="yui_3_16_0_1_1456619427414_9886" style="display: block;"> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;" id="yui_3_16_0_1_1456619427414_9885"> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;" id="yui_3_16_0_1_1456619427414_9884"> <div dir="ltr" id="yui_3_16_0_1_1456619427414_9883"> <font size="2" face="Arial" id="yui_3_16_0_1_1456619427414_9882"> <hr size="1"> <b><span style="font-weight:bold;">From:</span></b> Brian Cox via Personal_Submersibles <personal_submersibles@psubs.org><br> <b><span style="font-weight: bold;">To:</span></b> Personal Submersibles General Discussion <personal_submersibles@psubs.org> <br> <b><span style="font-weight: bold;">Sent:</span></b> Sunday, February 28, 2016 7:20 PM<br> <b><span style="font-weight: bold;">Subject:</span></b> Re: [PSUBS-MAILIST] Acceptable cabin pressure swing<br> </font> </div> <div class="y_msg_container" id="yui_3_16_0_1_1456619427414_10008"><br><div id="yiv5168210388"><div id="yui_3_16_0_1_1456619427414_10007"><div style="font-family:Arial, sans-serif;font-size:10pt;" id="yui_3_16_0_1_1456619427414_10006"><div>I guess if the relief valve is more than a couple of feet below the water line, that would be a 1/2 psi per foot, which would render the valve superfluous.</div><div> </div><div>Brian</div><div class="yiv5168210388yqt6026754782" id="yiv5168210388yqt92546"><div id="yui_3_16_0_1_1456619427414_10005"><br clear="none"><br clear="none">--- personal_submersibles@psubs.org wrote:<br clear="none"><br clear="none">From: Hugh Fulton via Personal_Submersibles <personal_submersibles@psubs.org><br clear="none">To: "'Personal Submersibles General Discussion'" <personal_submersibles@psubs.org><br clear="none">Subject: Re: [PSUBS-MAILIST] Acceptable cabin pressure swing<br clear="none">Date: Sun, 28 Feb 2016 17:36:06 +1300<br clear="none"><br clear="none"></div><div id="yui_3_16_0_1_1456619427414_10018"><div id="yui_3_16_0_1_1456619427414_10017"><span style="color:rgb(31, 73, 125);" id="yui_3_16_0_1_1456619427414_10016">I know Emile has had it working but is it possible for the O’ring to dislodge with flow. I think the the O’ring should be more captive like in a dovetail groove in Parker book. It is nice and simple but it should be tested at different pressures and flows. Comments?</span></div></div><div id="yui_3_16_0_1_1456619427414_10010"><div id="yui_3_16_0_1_1456619427414_10009"><span style="color:rgb(31, 73, 125);">Hugh</span><span lang="EN-NZ" style="color:rgb(31, 73, 125);"></span></div></div></div></div><div class="yiv5168210388yqt6026754782" id="yiv5168210388yqt03206"><div><span style="color:rgb(31, 73, 125);"></span> </div><div><div style="border-width:1pt medium medium;border-style:solid none none;border-color:rgb(181, 196, 223) currentColor currentColor;padding:3pt 0cm 0cm;"></div></div><div id="yui_3_16_0_1_1456619427414_10020"><b><span style="">From:</span></b><span style="" id="yui_3_16_0_1_1456619427414_10021"> Personal_Submersibles [mailto:personal_submersibles-bounces@psubs.org] <b>On Behalf Of </b>Alan James via Personal_Submersibles<br clear="none"><b>Sent:</b> Sunday, 28 February 2016 7:59 a.m.<br clear="none"><b>To:</b> Personal Submersibles General Discussion<br clear="none"><b>Subject:</b> Re: [PSUBS-MAILIST] Acceptable cabin pressure swing</span></div><div> </div><div></div><div><div></div></div><div style="background:white;"><span style="color:black;">I sent this attachment & a couple of pictures but I haven't seen it yet,</span></div><div></div><div style="background:white;" id="yui_3_16_0_1_1456619427414_10022"><span style="color:black;">so here is just the attachment only.</span></div><div></div><div style="background:white;"><span style="color:black;">This could be adapted in to some sort of snorkel for air on the surface.</span></div><div></div><div style="background:white;"><span style="color:black;">Alan</span></div><div></div><div style="background:white;margin-bottom:12pt;"><span style="color:black;"></span> </div><div><div><div><div><div align="center" style="background:white;text-align:center;"><span style="color:black;"></span><hr align="center" width="100%" size="1"></div></div></div></div></div><div style="background:white;" id="yui_3_16_0_1_1456619427414_10024"><b id="yui_3_16_0_1_1456619427414_10026"><span style="color:black;" id="yui_3_16_0_1_1456619427414_10025">From:</span></b><span style="color:black;" id="yui_3_16_0_1_1456619427414_10023"> Alec Smyth via Personal_Submersibles <<a rel="nofollow" shape="rect" ymailto="mailto:personal_submersibles@psubs.org" target="_blank" href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>><br clear="none"><b>To:</b> Personal Submersibles General Discussion <<a rel="nofollow" shape="rect" ymailto="mailto:personal_submersibles@psubs.org" target="_blank" href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>> <br clear="none"><b>Sent:</b> Sunday, February 28, 2016 7:41 AM<br clear="none"><b>Subject:</b> Re: [PSUBS-MAILIST] Acceptable cabin pressure swing</span><span style="color:black;"></span></div><div></div><div style="background:white;"><span style="color:black;"></span> </div><div><div><div></div></div></div><div style="background:white;" id="yui_3_16_0_1_1456619427414_10028"><span style="color:black;" id="yui_3_16_0_1_1456619427414_10027">The problem with that valve is that it's just got a 1/4" diameter, and you really want it to handle large volumes. Emile and I as mentioned built our own and they're really easy to make. Interestingly we made them independently but what we came up with is identical. I know Emile posted his design here a while back, so it must be somewhere in the archives. I never made a drawing of mine, just made the actual valve directly since it's so straightforward. It's machined from a SS round and consists of just two parts. The main body is a cylinder with a bunch of holes drilled through it, and one central hole for the stem. This cylinder is welded into the hull. The other part is the cap, a shorter length cut from the same solid round but with an O ring groove around the edge and no holes. The stem goes through the body and screws into the cap. You put a spring on the stem and a wing nut to adjust the cracking pressure. That's it. If interior pressure is stronger that the spring, the cap lifts and in so doing opens all the holes. </span></div><div></div><div style="background:white;"><span style="color:black;"></span> </div><div></div><div style="background:white;"><span style="color:black;">Best,</span></div><div></div><div style="background:white;"><span style="color:black;"><br clear="none">Alec</span></div><div></div><div style="background:white;"><span style="color:black;"></span> </div><div><div></div></div><div style="background:white;"><span style="color:black;">On Sat, Feb 27, 2016 at 10:07 AM, Cliff Redus via Personal_Submersibles <<a rel="nofollow" shape="rect" ymailto="mailto:personal_submersibles@psubs.org" target="_blank" href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>> wrote:<br clear="none"><br clear="none"></span></div><div style="background:white;"><span style="color:black;">Brian, see McMaster Carr part number 4620K41. This has a 1 psi cracking pressure, not 0.5 psi that I mentioned earlier.</span></div><div></div><div style="background:white;"><span style="color:black;"></span> </div><div></div><div style="background:white;"><span style="color:black;">Cliff</span></div><div><div></div></div><div style="background:white;"><span style="color:black;"><br clear="none"><br clear="none">On Thursday, February 25, 2016, Brian Cox via Personal_Submersibles <<a rel="nofollow" shape="rect" ymailto="mailto:personal_submersibles@psubs.org" target="_blank" href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>> wrote:<br clear="none"><br clear="none"></span></div><div><div></div></div><div style="background:white;"><span style="color:black;">Cliff, Where did you find that 1/2 psi relief valve?</span></div><div></div><div style="background:white;"><span style="color:black;"></span> </div><div></div><div style="background:white;margin-bottom:12pt;"><span style="color:black;">Brian Cox<br clear="none"><br clear="none">--- <span>personal_submersibles@psubs.org</span> wrote:<br clear="none"><br clear="none">From: Cliff Redus via Personal_Submersibles <<span>personal_submersibles@psubs.org</span>><br clear="none">To: Personal Submersibles General Discussion <<span>personal_submersibles@psubs.org</span>><br clear="none">Subject: Re: [PSUBS-MAILIST] Acceptable cabin pressure swing<br clear="none">Date: Thu, 25 Feb 2016 19:05:00 -0600</span></div><div><div></div></div><div style="background:white;"><span style="color:black;">Jon for my boat, I have a pressure relief valve with a 1/2 psi cracking pressure to vent pressure while on the surface. I have a high cabin pressure alarm that triggers at 20 psia (5.3 psig) and a cabin lower pressure alarm set at 12 psia (-2.7 psig). In the PLC I also record and display the cabin pressure at the time the hatch is closed and log all alarm states every second. </span></div><div></div><div style="background:white;"><span style="color:black;"></span> </div><div></div><div style="background:white;"><span style="color:black;">I have never had either a high or low cabin pressure alarm while diving. I have had elevated cabin pressure caused by accidently having the backup manual O2 value open and a leak in an air fitting on anther occasion.</span></div><div></div><div style="background:white;"><span style="color:black;"></span> </div><div></div><div style="background:white;"><span style="color:black;">Cliff</span></div><div></div><div style="background:white;"><span style="color:black;"></span> </div><div></div><div style="background:white;"><span style="color:black;">On Wed, Feb 24, 2016 at 1:12 PM, Jon Wallace via Personal_Submersibles <<span>personal_submersibles@psubs.org</span>> wrote:<br clear="none"><br clear="none"></span></div><div style="background:white;"><span style="color:black;"><br clear="none">I think this is somewhat subjective but what is general consensus on maximum cabin pressure swing (higher/lower) relative to hatch closing at the start of a dive before setting off alarms? My thought is that an alarm should sound well before any point of emergency. I'm considering sounding a warning at 2psi +/- and an alarm at 4psi +/- but I'm not sure if this is too strict.<br clear="none"><br clear="none">Jon<br clear="none">_______________________________________________<br clear="none">Personal_Submersibles mailing list<br clear="none"><span>Personal_Submersibles@psubs.org</span><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></span></div><div style="background:white;"><span style="color:black;"></span> </div><div style="background:white;"><span style="color:black;">_______________________________________________ Personal_Submersibles mailing list <span>Personal_Submersibles@psubs.org</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></div><div style="background:white;margin-bottom:12pt;"><span style="color:black;"><br clear="none">_______________________________________________<br clear="none">Personal_Submersibles mailing list<br clear="none"><a rel="nofollow" shape="rect" ymailto="mailto:Personal_Submersibles@psubs.org" target="_blank" href="mailto:Personal_Submersibles@psubs.org">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></span></div><div style="background:white;"><span style="color:black;"></span> </div><div style="background:white;"><span style="color:black;"></span> </div><div></div><div style="background:white;"><span style="color:black;">_______________________________________________<br clear="none">Personal_Submersibles mailing list<br clear="none"><a rel="nofollow" shape="rect" ymailto="mailto:Personal_Submersibles@psubs.org" target="_blank" href="mailto:Personal_Submersibles@psubs.org">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></span></div></div><div style="background:white;margin-bottom:12pt;"><span style="color:black;"></span> _______________________________________________
Personal_Submersibles mailing list
<a rel="nofollow" shape="rect" href="">Personal_Submersibles@psubs.org</a>
<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>
</div></div></div><br><div class="yqt6026754782" id="yqt51245">_______________________________________________<br clear="none">Personal_Submersibles mailing list<br clear="none"><a shape="rect" ymailto="mailto:Personal_Submersibles@psubs.org" href="mailto:Personal_Submersibles@psubs.org">Personal_Submersibles@psubs.org</a><br clear="none"><a shape="rect" href="http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles" target="_blank">http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles</a><br clear="none"></div><br><br></div> </div> </div> </div></div></body></html>