<DIV style="font-family:Arial, sans-serif; font-size:10pt;"><DIV>probably will just end up letting my hatch burp</DIV><DIV> </DIV><DIV>Brian<BR><BR>--- personal_submersibles@psubs.org wrote:<BR><BR>From: Alan James via Personal_Submersibles <personal_submersibles@psubs.org><BR>To: Personal Submersibles General Discussion <personal_submersibles@psubs.org><BR>Subject: Re: [PSUBS-MAILIST] Acceptable cabin pressure swing<BR>Date: Sun, 28 Feb 2016 07:35:35 +0000 (UTC)<BR><BR></DIV><DIV style="color: rgb(0, 0, 0); font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);"><DIV><SPAN>Brian,</SPAN></DIV><DIV dir="ltr"><SPAN>one way round that would be to weld a tube to the port below the</SPAN></DIV><DIV dir="ltr"><SPAN>water line & have the tube coming up to the top of the sub with the exhaust valve</SPAN></DIV><DIV dir="ltr"><SPAN>mounted on that. However it would be difficult to set up a mechanism to plunge</SPAN></DIV><DIV dir="ltr"><SPAN>it.</SPAN></DIV><DIV dir="ltr"><SPAN>Alan</SPAN></DIV><DIV><BR><BR></DIV><DIV style="display: block;"> <DIV style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;"> <DIV style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;"> <DIV dir="ltr"> <FONT face="Arial" size="2"> <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><BR><DIV><DIV><DIV style="font-family: Arial, sans-serif; font-size: 10pt;"><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><DIV><BR><BR>--- personal_submersibles@psubs.org wrote:<BR><BR>From: Hugh Fulton via Personal_Submersibles <personal_submersibles@psubs.org><BR>To: "'Personal Submersibles General Discussion'" <personal_submersibles@psubs.org><BR>Subject: Re: [PSUBS-MAILIST] Acceptable cabin pressure swing<BR>Date: Sun, 28 Feb 2016 17:36:06 +1300<BR><BR></DIV><DIV><DIV><SPAN style="color: rgb(31, 73, 125);">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><DIV><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><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><B><SPAN>From:</SPAN></B><SPAN> 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</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;"><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 width="100%" size="1" align="center"></DIV></DIV></DIV></DIV></DIV><DIV style="background: white;"><B><SPAN style="color: black;">From:</SPAN></B><SPAN style="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="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;"><SPAN style="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. </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>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 href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</A>> wrote:<BR><BR></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><BR>On Thursday, February 25, 2016, Brian Cox via Personal_Submersibles <<A href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</A>> wrote:<BR><BR></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><BR>--- <SPAN>personal_submersibles@psubs.org</SPAN> wrote:<BR><BR>From: Cliff Redus via Personal_Submersibles <<SPAN>personal_submersibles@psubs.org</SPAN>><BR>To: Personal Submersibles General Discussion <<SPAN>personal_submersibles@psubs.org</SPAN>><BR>Subject: Re: [PSUBS-MAILIST] Acceptable cabin pressure swing<BR>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><BR></SPAN></DIV><DIV style="background: white;"><SPAN style="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>Personal_Submersibles@psubs.org</SPAN><BR><A 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 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>_______________________________________________<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">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>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">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> _______________________________________________
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