<html><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_1434757775185_3704"><span>Any link to it Brian?</span></div><div id="yui_3_16_0_1_1434757775185_3704"><span id="yui_3_16_0_1_1434757775185_4188">I think Emile posted his over pressure valve design at one time.</span></div><div id="yui_3_16_0_1_1434757775185_3704"><span id="yui_3_16_0_1_1434757775185_4189">It has a plunger for manually releasing the last bit of pressure.</span></div><div id="yui_3_16_0_1_1434757775185_3704"><span id="yui_3_16_0_1_1434757775185_4190">With a bit of thought you could incorporate a snorkel system &</span></div><div id="yui_3_16_0_1_1434757775185_3704" dir="ltr">circulate air around the hull through it.</div><div id="yui_3_16_0_1_1434757775185_3704" dir="ltr">Another thought is to use Vance's Top Hat valve design for ballast tanks,</div><div id="yui_3_16_0_1_1434757775185_3704" dir="ltr">& use a weak spring.</div><div id="yui_3_16_0_1_1434757775185_3704" dir="ltr">Alan</div><br> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;" id="yui_3_16_0_1_1434757775185_3792"> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;" id="yui_3_16_0_1_1434757775185_3791"> <div dir="ltr" id="yui_3_16_0_1_1434757775185_3796"> <hr size="1" id="yui_3_16_0_1_1434757775185_4191"> <font size="2" face="Arial" id="yui_3_16_0_1_1434757775185_3795"> <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> Saturday, June 20, 2015 11:15 AM<br> <b><span style="font-weight: bold;">Subject:</span></b> Re: [PSUBS-MAILIST] over pressure valve<br> </font> </div> <div class="y_msg_container" id="yui_3_16_0_1_1434757775185_3790"><br>I found a really nice 1" SS spring check valve that I think would work really nicely as an OP valve, the spring is so light that the differential would be next to nothing. I also looked at an interesting ball bearing check valve that works on just gravity, which would work as well, but it wasn't SS.<br><br>Brian<br><br>--- <a ymailto="mailto:personal_submersibles@psubs.org" href="mailto:personal_submersibles@psubs.org" id="yui_3_16_0_1_1434757775185_4553">personal_submersibles@psubs.org</a> wrote:<br><br>From: hank pronk via Personal_Submersibles <<a ymailto="mailto:personal_submersibles@psubs.org" href="mailto:personal_submersibles@psubs.org" id="yui_3_16_0_1_1434757775185_3794">personal_submersibles@psubs.org</a>><br>To: Personal Submersibles General Discussion <<a ymailto="mailto:personal_submersibles@psubs.org" href="mailto:personal_submersibles@psubs.org" id="yui_3_16_0_1_1434757775185_3793">personal_submersibles@psubs.org</a>><br>Subject: Re: [PSUBS-MAILIST] over pressure valve<br>Date: Fri, 19 Jun 2015 14:28:43 -0700<br><br><br>Alec,<br>At first I resisted the notion of thermal expansion, but I was thinking in terms of heat generated from motor use. I didn't consider the temperature change from the sun on a black motor until the light went on :-)<br>I have changed my p trap ss tube to a larger hose so there is more air volume to work with. I am ready to test that part. Now I have to fix my bent up rudder :-(<br>Hank--------------------------------------------<br>On Fri, 6/19/15, Alec Smyth via Personal_Submersibles <<a ymailto="mailto:personal_submersibles@psubs.org" href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>> wrote:<br><br> Subject: Re: [PSUBS-MAILIST] over pressure valve<br> To: "Personal Submersibles General Discussion" <<a ymailto="mailto:personal_submersibles@psubs.org" href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>><br> Received: Friday, June 19, 2015, 5:03 PM<br> <br> Oh! Well I<br> suppose it just depends on the volume the valve can handle.<br> This is an interesting calculation, which I have not done<br> but should. In general, these valves should handle pretty<br> huge flow rates. But you're right, its basic to surface<br> very slowly when there's any over-pressure - normally we<br> dive with under-pressure. For a K-boat sized hatch, an<br> over-pressure of 1/4 psi translates to a force of 95lbs<br> trying to pull the dome out of the hatch ring. I know<br> Snoopy's dome stays put at 1/4 psi, but I wouldn't<br> take it any further than that just in case. <br> BTW, on the subject of calculations<br> and changing topics back to the recent thruster compensation<br> thread, you were right about the temperature change. The<br> volume I had to compensate was a combination of thermal<br> contraction and air bubble. The air bubble was of unknown<br> size, but I ran the numbers on the thermal contraction alone<br> and it is enough to cause the problem. The little hose only<br> has a an internal volume of 10ml. The thermal contraction of<br> the oil turned out to be 16ml - add to that the volume of<br> the unknown bubble, and you can see the hose was inadequate<br> even if it squashed to zero internal volume. I am now<br> installing bellows bottles in place of the little hoses,<br> with a capacity of 60ml. And a better filling method that<br> should eliminate the bubble. You'd think I wasn't an<br> engineer, assuming the effect of thermal contraction to be<br> negligible. Its easy to focus the calculations on big items<br> like hull strength or stability and make assumptions about<br> the little stuff.<br> Best,<br> Alec<br> On Fri, Jun 19, 2015 at<br> 4:19 PM, hank pronk via Personal_Submersibles <<a ymailto="mailto:personal_submersibles@psubs.org" href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>><br> wrote:<br> <br> <br> You have to be experienced to surface slowly and hover while<br> the valve leaks out the<br> air.--------------------------------------------<br> <br> On Fri, 6/19/15, Alec Smyth via<br> Personal_Submersibles <<a ymailto="mailto:personal_submersibles@psubs.org" href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>><br> wrote:<br> <br> <br> <br> Subject: Re: [PSUBS-MAILIST] over pressure valve<br> <br> To: "Personal Submersibles General Discussion"<br> <<a ymailto="mailto:personal_submersibles@psubs.org" href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>><br> <br> Received: Friday, June 19, 2015, 4:16 PM<br> <br> <br> <br> I<br> <br> don't get the "in the hands" part... its<br> <br> completely automatic.<br> <br> On Fri, Jun 19, 2015 at<br> <br> 4:09 PM, hank pronk via Personal_Submersibles <<a ymailto="mailto:personal_submersibles@psubs.org" href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>><br> <br> wrote:<br> <br> <br> <br> <br> <br> Agreed,<br> <br> <br> <br> In the hands of an experienced submarine operator an<br> over<br> <br> pressure valve is safe, providing it is large enough. <br> I<br> <br> have not seen an example of a large enough OPV. A<br> simple<br> <br> valve in the hatch will do the same job, just need an<br> <br> umbrella :-)<br> <br> <br> <br> The noise of a compressor is a welcome sound if it<br> means<br> <br> keeping the dome on the sub :-)<br> <br> <br> <br> Hank--------------------------------------------<br> <br> <br> <br> On Fri, 6/19/15, Carsten Standfuß" via<br> <br> Personal_Submersibles <<a ymailto="mailto:personal_submersibles@psubs.org" href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>><br> <br> wrote:<br> <br> <br> <br> <br> <br> <br> <br> Subject: Re: [PSUBS-MAILIST] over pressure valve<br> <br> <br> <br> To: "Personal Submersibles General<br> Discussion"<br> <br> <<a ymailto="mailto:personal_submersibles@psubs.org" href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>><br> <br> <br> <br> Received: Friday, June 19, 2015, 2:47 PM<br> <br> <br> <br> <br> <br> <br> <br> But a overpressure vale works<br> <br> <br> <br> full auto. A compressor<br> <br> <br> <br> not. <br> <br> <br> <br> <br> <br> <br> <br> A OPV needs<br> <br> <br> <br> no energy - but a compressor did.<br> <br> <br> <br> <br> <br> <br> <br> <br> <br> <br> <br> A OPV needs no room - but<br> <br> <br> <br> a compressor did.<br> <br> <br> <br> <br> <br> <br> <br> And a<br> <br> <br> <br> compressor is<br> <br> <br> <br> a noisy solution..<br> <br> <br> <br> <br> <br> <br> <br> vbr<br> <br> <br> <br> Carsten<br> <br> <br> <br> <br> <br> <br> <br> <br> <br> <br> <br> <br> <br> <br> <br> "hank<br> <br> <br> <br> pronk via Personal_Submersibles" <<a ymailto="mailto:personal_submersibles@psubs.org" href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>><br> <br> <br> <br> schrieb:<br> <br> <br> <br> > Personally I think an onboard<br> <br> <br> <br> compressor is a much safer option than an over<br> pressure<br> <br> <br> <br> valve. There are multiple safety benefits to an<br> <br> onboard<br> <br> <br> <br> compressor, over pressure being the biggy. With a<br> <br> <br> <br> compressor you can get rid of the pressure without<br> <br> surfacing<br> <br> <br> <br> and trying to control a perfect ascent. With the<br> OPV<br> <br> you<br> <br> <br> <br> have to surface a bit and let air out and wait then<br> <br> surface<br> <br> <br> <br> more and wait and so on. You can't just surface<br> and<br> <br> hope<br> <br> <br> <br> the valve keeps up with the demand. This is more<br> <br> important<br> <br> <br> <br> for subs with large domes.<br> <br> <br> <br> > The next<br> <br> <br> <br> benefit to a compressor is, if you lost all your air,<br> <br> you<br> <br> <br> <br> surface by dropping your weight. In my case the<br> weight<br> <br> is<br> <br> <br> <br> small and I would also drop the thruster and tail<br> <br> assembly.<br> <br> <br> <br> Still, not much sub out of the water. With the<br> <br> compressor,<br> <br> <br> <br> I can open my vent valve in the hatch and use the<br> <br> compressor<br> <br> <br> <br> to fill the ballast tanks.<br> <br> <br> <br> > Hank<br> <br> <br> <br> ><br> <br> <br> <br> _______________________________________________<br> <br> <br> <br> > Personal_Submersibles mailing list<br> <br> <br> <br> > <a ymailto="mailto:Personal_Submersibles@psubs.org" href="mailto:Personal_Submersibles@psubs.org">Personal_Submersibles@psubs.org</a><br> <br> <br> <br> > <a href="http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles" target="_blank">http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles</a><br> <br> <br> <br> ><br> <br> <br> <br> <br> <br> <br> <br> -----Inline Attachment Follows-----<br> <br> <br> <br> <br> <br> <br> <br> _______________________________________________<br> <br> <br> <br> Personal_Submersibles mailing list<br> <br> <br> <br> <a ymailto="mailto:Personal_Submersibles@psubs.org" href="mailto:Personal_Submersibles@psubs.org">Personal_Submersibles@psubs.org</a><br> <br> <br> <br> <a href="http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles" target="_blank">http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles</a><br> <br> <br> <br> <br> <br> <br> <br> <br> <br> <br> <br> _______________________________________________<br> <br> <br> <br> Personal_Submersibles mailing list<br> <br> <br> <br> <a ymailto="mailto:Personal_Submersibles@psubs.org" href="mailto:Personal_Submersibles@psubs.org">Personal_Submersibles@psubs.org</a><br> <br> <br> <br> <a href="http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles" target="_blank">http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles</a><br> <br> <br> <br> <br> <br> <br> <br> -----Inline Attachment Follows-----<br> <br> <br> <br> _______________________________________________<br> <br> Personal_Submersibles mailing list<br> <br> <a ymailto="mailto:Personal_Submersibles@psubs.org" href="mailto:Personal_Submersibles@psubs.org">Personal_Submersibles@psubs.org</a><br> <br> <a href="http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles" target="_blank">http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles</a><br> <br> <br> <br> <br> <br> _______________________________________________<br> <br> Personal_Submersibles mailing list<br> <br> <a ymailto="mailto:Personal_Submersibles@psubs.org" href="mailto:Personal_Submersibles@psubs.org">Personal_Submersibles@psubs.org</a><br> <br> <a href="http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles" target="_blank">http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles</a><br> <br> <br> <br> -----Inline Attachment Follows-----<br> <br> _______________________________________________<br> Personal_Submersibles mailing list<br> <a ymailto="mailto:Personal_Submersibles@psubs.org" 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><br> <br><br>_______________________________________________<br>Personal_Submersibles mailing list<br><a ymailto="mailto:Personal_Submersibles@psubs.org" 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><br><br><br><br>_______________________________________________<br>Personal_Submersibles mailing list<br><a ymailto="mailto:Personal_Submersibles@psubs.org" 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><br><br><br></div> </div> </div> </div></body></html>