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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>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?<o:p></o:p></span></p><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Hugh</span><span lang=EN-NZ style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p></o:p></span></p></div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0cm 0cm 0cm'><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>Alan James via Personal_Submersibles<br><b>Sent:</b> Sunday, 28 February 2016 7:59 a.m.<br><b>To:</b> Personal Submersibles General Discussion<br><b>Subject:</b> Re: [PSUBS-MAILIST] Acceptable cabin pressure swing<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><div><div id="yui_3_16_0_1_1456599241714_2752"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'>I sent this attachment & a couple of pictures but I haven't seen it yet,<o:p></o:p></span></p></div><div id="yui_3_16_0_1_1456599241714_2752"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'>so here is just the attachment only.<o:p></o:p></span></p></div><div id="yui_3_16_0_1_1456599241714_2752"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'>This could be adapted in to some sort of snorkel for air on the surface.<o:p></o:p></span></p></div><div id="yui_3_16_0_1_1456599241714_2752"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'>Alan<o:p></o:p></span></p></div><div id="yui_3_16_0_1_1456599241714_2753"><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></div><div id="yui_3_16_0_1_1456599241714_2759"><div id="yui_3_16_0_1_1456599241714_2758"><div id="yui_3_16_0_1_1456599241714_2757"><div id="yui_3_16_0_1_1456599241714_2756"><div class=MsoNormal align=center style='text-align:center;background:white'><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'><hr size=1 width="100%" align=center></span></div><p class=MsoNormal style='background:white'><b><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'>From:</span></b><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'> Alec Smyth via Personal_Submersibles <<a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>><br><b>To:</b> Personal Submersibles General Discussion <<a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>> <br><b>Sent:</b> Sunday, February 28, 2016 7:41 AM<br><b>Subject:</b> Re: [PSUBS-MAILIST] Acceptable cabin pressure swing</span><span style='font-family:"Helvetica","sans-serif";color:black'><o:p></o:p></span></p></div><div id="yui_3_16_0_1_1456599241714_2760"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'><o:p> </o:p></span></p><div id=yiv5995885318><div id="yui_3_16_0_1_1456599241714_2857"><div id="yui_3_16_0_1_1456599241714_2856"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'>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. <o:p></o:p></span></p><div id="yui_3_16_0_1_1456599241714_3116"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'><o:p> </o:p></span></p></div><div><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'>Best,<o:p></o:p></span></p></div><div id="yui_3_16_0_1_1456599241714_2858"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'><br>Alec<o:p></o:p></span></p></div></div><div id="yui_3_16_0_1_1456599241714_2864"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'><o:p> </o:p></span></p><div id=yiv5995885318yqtfd23793><div id="yui_3_16_0_1_1456599241714_2863"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'>On Sat, Feb 27, 2016 at 10:07 AM, Cliff Redus via Personal_Submersibles <<a href="mailto:personal_submersibles@psubs.org" target="_blank" id="yui_3_16_0_1_1456599241714_3061">personal_submersibles@psubs.org</a>> wrote:<br><br><o:p></o:p></span></p><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'>Brian, see McMaster Carr part number 4620K41. This has a 1 psi cracking pressure, not 0.5 psi that I mentioned earlier.<o:p></o:p></span></p><div id="yui_3_16_0_1_1456599241714_3060"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'><o:p> </o:p></span></p></div><div id="yui_3_16_0_1_1456599241714_2861"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'>Cliff<o:p></o:p></span></p><div id="yui_3_16_0_1_1456599241714_2860"><div id="yui_3_16_0_1_1456599241714_2859"><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'><br><br>On Thursday, February 25, 2016, Brian Cox via Personal_Submersibles <<a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.org</a>> wrote:<br><br><o:p></o:p></span></p><div id="yui_3_16_0_1_1456599241714_2866"><div><p class=MsoNormal style='background:white'><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'>Cliff, Where did you find that 1/2 psi relief valve?<o:p></o:p></span></p></div><div id="yui_3_16_0_1_1456599241714_3059"><p class=MsoNormal style='background:white'><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'> <o:p></o:p></span></p></div><div id="yui_3_16_0_1_1456599241714_2865"><p class=MsoNormal style='margin-bottom:12.0pt;background:white'><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'>Brian Cox<br><br>--- <span class=MsoHyperlink>personal_submersibles@psubs.org</span> wrote:<br><br>From: Cliff Redus via Personal_Submersibles <<span class=MsoHyperlink>personal_submersibles@psubs.org</span>><br>To: Personal Submersibles General Discussion <<span class=MsoHyperlink>personal_submersibles@psubs.org</span>><br>Subject: Re: [PSUBS-MAILIST] Acceptable cabin pressure swing<br>Date: Thu, 25 Feb 2016 19:05:00 -0600<o:p></o:p></span></p></div><div id="yui_3_16_0_1_1456599241714_2869"><div id="yui_3_16_0_1_1456599241714_2868"><p class=MsoNormal style='background:white'><span style='font-size:10.0pt;font-family:"Arial","sans-serif";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. <o:p></o:p></span></p></div><div id="yui_3_16_0_1_1456599241714_2870"><p class=MsoNormal style='background:white'><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'><o:p> </o:p></span></p></div><div id="yui_3_16_0_1_1456599241714_2871"><p class=MsoNormal style='background:white'><span style='font-size:10.0pt;font-family:"Arial","sans-serif";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.<o:p></o:p></span></p></div><div id="yui_3_16_0_1_1456599241714_2872"><p class=MsoNormal style='background:white'><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'><o:p> </o:p></span></p></div><div><p class=MsoNormal style='background:white'><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'>Cliff<o:p></o:p></span></p></div></div><div id="yui_3_16_0_1_1456599241714_3020"><p class=MsoNormal style='background:white'><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'><o:p> </o:p></span></p><div id="yui_3_16_0_1_1456599241714_3022"><p class=MsoNormal style='background:white'><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'>On Wed, Feb 24, 2016 at 1:12 PM, Jon Wallace via Personal_Submersibles <<span class=MsoHyperlink>personal_submersibles@psubs.org</span>> wrote:<br><br><o:p></o:p></span></p><p class=MsoNormal style='background:white'><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'><br>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><br>Jon<br>_______________________________________________<br>Personal_Submersibles mailing list<br><span class=MsoHyperlink>Personal_Submersibles@psubs.org</span><br><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></p></div><p class=MsoNormal style='background:white'><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'><o:p> </o:p></span></p></div><p class=MsoNormal style='background:white'><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:black'>_______________________________________________ Personal_Submersibles mailing list <span class=MsoHyperlink>Personal_Submersibles@psubs.org</span> <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></p></div></div></div></div><p class=MsoNormal style='margin-bottom:12.0pt;background:white'><span style='font-family:"Helvetica","sans-serif";color:black'><br>_______________________________________________<br>Personal_Submersibles mailing list<br><a href="mailto:Personal_Submersibles@psubs.org" target="_blank">Personal_Submersibles@psubs.org</a><br><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></p></div><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'><o:p> </o:p></span></p></div></div></div></div><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'><o:p> </o:p></span></p><div id=yqtfd70738><p class=MsoNormal style='background:white'><span style='font-family:"Helvetica","sans-serif";color:black'>_______________________________________________<br>Personal_Submersibles mailing list<br><a href="mailto:Personal_Submersibles@psubs.org">Personal_Submersibles@psubs.org</a><br><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></p></div><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></div></div></div></div></div></div></body></html>