<html><head></head><body><p dir="ltr">Yes. It makes more sense, IMO, to run tubes to the areas of interest, because they're easier to seal through pressure boundaries than cables, and less worry to subject to seawater, external pressure and incidental contact. I'm definitely a fan of minimal, protected and noise immune cable runs. One central vacuum pump serving a manifold with six solenoid valves and tubing run to each hatch flange, and a pressure transducer on each of those lines, centrally located in the (hopefully) dry 1 atm cabin. That doesn't alleviate the need for high pressure sensors though - the piping runs from the lockout compartment are still at lockout compartment pressure when those hatches are open.</p>
<p dir="ltr">Sean<br>
</p>
<br><br><div class="gmail_quote">On March 2, 2016 7:28:13 PM MST, Alan James via Personal_Submersibles <personal_submersibles@psubs.org> wrote:<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<div style="color:#000; background-color:#fff; font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:16px"><div id="yiv8154287830"><div id="yui_3_16_0_1_1456970978637_2988"><div style="color:#000;background-color:#fff;font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:16px;" id="yui_3_16_0_1_1456970978637_2987"><div id="yiv8154287830yui_3_16_0_1_1456970247825_2749"><span id="yiv8154287830yui_3_16_0_1_1456970247825_2963">You will need to have wires from the transducers running through hull walls</span></div><div dir="ltr" id="yiv8154287830yui_3_16_0_1_1456970247825_2749"><span id="yiv8154287830yui_3_16_0_1_1456970247825_2962">to your monitoring point. </span> If you had a central pump in the 1 atm compartment </div><div dir="ltr" id="yiv8154287830yui_3_16_0_1_1456970247825_2749"><span id="yui_3_16_0_1_1456970978637_5844">you would need </span>pipes running through hull walls
to each individual hatch wouldn't you?</div><div dir="ltr" id="yiv8154287830yui_3_16_0_1_1456970247825_2749">If you had a line coming from your vacuum pump in the 1atm compartment you could have </div><div dir="ltr" id="yiv8154287830yui_3_16_0_1_1456970247825_2749">it running to a 6 port manifold with 6 solenoid valves followed by 6 pressure sensors switching </div><div dir="ltr" id="yiv8154287830yui_3_16_0_1_1456970247825_2749">the solenoid valves, then through the hull walls. This would save you having electrical through </div><div dir="ltr" id="yiv8154287830yui_3_16_0_1_1456970247825_2749">hulls & high pressure sensors. Or have I got it wrong??</div><div dir="ltr" id="yiv8154287830yui_3_16_0_1_1456970247825_2749"><span>Cheers Alan</span></div><div dir="ltr" id="yiv8154287830yui_3_16_0_1_1456970247825_2749"><span><br /></span></div><div class="yiv8154287830qtdSeparateBR" id="yiv8154287830yui_3_16_0_1_1456970247825_2750"><br clear="none" /><br clear="none"
/></div></div></div></div><div class=".yiv8154287830yahoo_quoted" id="yui_3_16_0_1_1456970978637_3033"> <div id="yiv8154287830yui_3_16_0_1_1456970247825_2790" style="font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:16px;"> <div id="yiv8154287830yui_3_16_0_1_1456970247825_2789" style="font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:16px;"> <div class="qtdSeparateBR" id="yui_3_16_0_1_1456970978637_3032"><br /><br /></div><div class="yiv8154287830yqt9901746046" id="yiv8154287830yqt19680"><div dir="ltr" id="yiv8154287830yui_3_16_0_1_1456970247825_2788"> <font id="yiv8154287830yui_3_16_0_1_1456970247825_2787" size="2" face="Arial"> </font><hr id="yiv8154287830yui_3_16_0_1_1456970247825_2961" size="1" /> <b><span style="font-weight:bold;">From:</span></b> Sean T. Stevenson via Personal_Submersibles <personal_submersibles@psubs.org><br clear="none" /> <b><span
style="font-weight:bold;">To:</span></b> Personal Submersibles General Discussion <personal_submersibles@psubs.org> <br clear="none" /> <b><span style="font-weight:bold;">Sent:</span></b> Thursday, March 3, 2016 10:53 AM<br clear="none" /> <b><span style="font-weight:bold;">Subject:</span></b> Re: [PSUBS-MAILIST] Hatch interlock<br clear="none" /> </div> <div class="yiv8154287830y_msg_container" id="yiv8154287830yui_3_16_0_1_1456970247825_2794"><br clear="none" /><div id="yiv8154287830"><div id="yiv8154287830yui_3_16_0_1_1456970247825_2793"><div dir="ltr" id="yiv8154287830yui_3_16_0_1_1456970247825_2792">I will have one transducer per hatch, so that I can track the interlock status and seal integrity per hatch. Each transducer is therefore exposed to whatever pressure exists at the flange between orings, which in the case of the lockout hatches must necessarily include the pressure at full lockout depth, because those flanges are exposed to full pressure when the lockout is
operated. This means that in order for this conceptual design to work, I must accept a larger range, lesser resolution measurement for those hatches, but it occurs to me now that in every case, I would need to accommodate the maximum anticipated pressure on either side of each hatch, if I expect to be able to track progressive seal leakage without damaging a transducer. Ergo, only the 1 atm spaces could make use of 0 - 15 psia transducers. The rest would have to be 0 - 250 psia or whatever, and I may require higher resolution signal conditioning (24 bit?) to eff!
ectively
measure the range below 1 ata.</div>
<div dir="ltr" id="yiv8154287830yui_3_16_0_1_1456970247825_2808">Sean<br clear="none" />
</div>
<br clear="none" /><br clear="none" /><div class="yiv8154287830yqt3134829238" id="yiv8154287830yqtfd33341"><div class="yiv8154287830gmail_quote" id="yiv8154287830yui_3_16_0_1_1456970247825_2795">On March 2, 2016 1:19:54 PM MST, Alan James via Personal_Submersibles <personal_submersibles@psubs.org> wrote:<blockquote class="yiv8154287830gmail_quote" id="yiv8154287830yui_3_16_0_1_1456970247825_2797" style="margin:0pt 0pt 0pt 0.8ex;border-left:1px solid rgb(204, 204, 204);padding-left:1ex;">
<div id="yiv8154287830yui_3_16_0_1_1456970247825_2796" style="color:#000;background-color:#fff;font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:16px;"><div id="yiv8154287830yui_3_16_0_1_1456947829988_2968">Sean,</div><div id="yiv8154287830yui_3_16_0_1_1456947829988_2968">why not leave the transducer in the 1 atm compartment & just attach it</div><div dir="ltr" id="yiv8154287830yui_3_16_0_1_1456947829988_2968">to the pipe from the compressor that would run through the wall to the various</div><div dir="ltr" id="yiv8154287830yui_3_16_0_1_1456947829988_2968">compartments & sealing flanges. There are of course other complications with</div><div dir="ltr" id="yiv8154287830yui_3_16_0_1_1456947829988_2968">releasing the vacuum pressure on the individual hatches.</div><div dir="ltr" id="yiv8154287830yui_3_16_0_1_1456947829988_2968">Alan</div><div dir="ltr" id="yiv8154287830yui_3_16_0_1_1456947829988_2968"><br clear="none" /></div><div
class="yiv8154287830qtdSeparateBR" id="yiv8154287830yui_3_16_0_1_1456947829988_2966"><br clear="none" /><br clear="none" /></div><div class="yiv8154287830yahoo_quoted" id="yiv8154287830yui_3_16_0_1_1456947829988_3032" style="display:block;"> <div id="yiv8154287830yui_3_16_0_1_1456947829988_3031" style="font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:16px;"> <div id="yiv8154287830yui_3_16_0_1_1456947829988_3030" style="font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:16px;"> <div dir="ltr" id="yiv8154287830yui_3_16_0_1_1456947829988_3029"> <font id="yiv8154287830yui_3_16_0_1_1456947829988_3033" size="2" face="Arial"> </font><hr id="yiv8154287830yui_3_16_0_1_1456947829988_3034" size="1" /><font id="yiv8154287830yui_3_16_0_1_1456947829988_3033" size="2" face="Arial"> <b><span style="font-weight:bold;">From:</span></b> Sean T. Stevenson via Personal_Submersibles
<personal_submersibles@psubs.org><br clear="none" /> <b><span style="font-weight:bold;">To:</span></b> Personal Submersibles General Discussion <personal_submersibles@psubs.org> <br clear="none" /> <b id="yui_3_16_0_1_1456970978637_10050"><span style="font-weight:bold;" id="yui_3_16_0_1_1456970978637_10049">Sent:</span></b> Thursday, March 3, 2016 8:35 AM<br clear="none" /> <b><span style="font-weight:bold;">Subject:</span></b> Re: [PSUBS-MAILIST] Hatch interlock<br clear="none" /> </font> </div> <div class="yiv8154287830y_msg_container" id="yiv8154287830yui_3_16_0_1_1456947829988_3282"><br clear="none" /><div id="yiv8154287830"><div id="yiv8154287830yui_3_16_0_1_1456947829988_3281"><div dir="ltr" id="yiv8154287830yui_3_16_0_1_1456947829988_3321">It is not the personnel transfer hatch that presents the problem, but rather the egress hatches in the lockout chamber, as those flanges will see the lockout pressure in normal operation. I can get away with a larger range
pressure transducer for those hatches, but then I lose measurement resolution.</div>
<div dir="ltr" id="yiv8154287830yui_3_16_0_1_1456947829988_3280">Sean<br clear="none" />
</div>
<br clear="none" /><br clear="none" /><div class="yiv8154287830yqt2702599122" id="yiv8154287830yqtfd73333"><div class="yiv8154287830gmail_quote" id="yiv8154287830yui_3_16_0_1_1456947829988_3283">On March 2, 2016 9:32:49 AM MST, Alan James via Personal_Submersibles <personal_submersibles@psubs.org> wrote:<blockquote class="yiv8154287830gmail_quote" id="yiv8154287830yui_3_16_0_1_1456947829988_3285" style="margin:0pt 0pt 0pt 0.8ex;border-left:1px solid rgb(204, 204, 204);padding-left:1ex;">
<div id="yiv8154287830yui_3_16_0_1_1456947829988_3284" style="color:#000;background-color:#fff;font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:16px;"><div id="yiv8154287830yui_3_16_0_1_1456935008552_12886"><span id="yiv8154287830yui_3_16_0_1_1456935008552_12916">Sean,</span></div><div dir="ltr" id="yiv8154287830yui_3_16_0_1_1456935008552_12886"><span id="yiv8154287830yui_3_16_0_1_1456935008552_12985">that sounds a good idea. Nuytco set the o-ring on the deep worker hatch externally with a vacuum</span></div><div dir="ltr" id="yiv8154287830yui_3_16_0_1_1456935008552_12886"><span id="yiv8154287830yui_3_16_0_1_1456935008552_12986">pump, but with your twin seal idea you could do this from within the sub without decreasing the hull pressure.</span></div><div dir="ltr" id="yiv8154287830yui_3_16_0_1_1456935008552_12889"><span id="yiv8154287830yui_3_16_0_1_1456935008552_12888"> If the transducers are just monitoring the vacuum between
the o-!
rings
can't the transducer be</span></div><div dir="ltr" id="yiv8154287830yui_3_16_0_1_1456935008552_12891"><span id="yiv8154287830yui_3_16_0_1_1456935008552_12890">m!
ounted
on the 1atm side of the diver lockout hatch & not be exposed to diver lockout pressure?</span></div><div dir="ltr" id="yiv8154287830yui_3_16_0_1_1456935008552_12885"><span>Alan</span></div><div dir="ltr" id="yiv8154287830yui_3_16_0_1_1456935008552_12858"><span><br clear="none" /></span></div><div class="yiv8154287830qtdSeparateBR" id="yiv8154287830yui_3_16_0_1_1456935008552_12856"><br clear="none" /><br clear="none" /></div><div class="yiv8154287830yahoo_quoted" id="yiv8154287830yui_3_16_0_1_1456935008552_12853" style="display:block;"> <div id="yiv8154287830yui_3_16_0_1_1456935008552_12852" style="font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:16px;"> <div id="yiv8154287830yui_3_16_0_1_1456935008552_12851" style="font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:16px;"> <div dir="ltr" id="yiv8154287830yui_3_16_0_1_1456935008552_12855"> <font
id="yiv8154287830yui_3_16_0_1_1456935008552_12854" size="2" face="Arial"> </font><hr id="yiv8154287830yui_3_16_0_1_1456935008552_12857" size="1" /><font id="yiv8154287830yui_3_16_0_1_1456947829988_3437" size="2" face="Arial">
<b><span style="font-weight:bold;">From:</span></b> Sean T. Stevenson via Personal_Submersibles <personal_submersibles@psubs.org><br clear="none" /> <b><span style="font-weight:bold;">To:</span></b> "personal_submersibles@psubs.org" <personal_submersibles@psubs.org> <br clear="none" /> <b><span style="font-weight:bold;">Sent:</span></b> Thursday, March 3, 2016 1:41 AM<br clear="none" /> <b id="yiv8154287830yui_3_16_0_1_1456935008552_12884"><span id="yiv8154287830yui_3_16_0_1_1456935008552_12883" style="font-weight:bold;">Subject:</span></b> [PSUBS-MAILIST] Hatch interlock<br clear="none" /> </font> </div> <div class="yiv8154287830y_msg_container" id="yiv8154287830yui_3_16_0_1_1456935008552_12850"><br clear="none" /><div id="yiv8154287830"><div dir="ltr" id="yiv8154287830yui_3_16_0_1_1456935008552_12859">Doing some further design on my lockout submersible project, I came up with a novel way to implement hatch interlocks, which doubles as a seal condition monitor, !
and a
means of establishing a preliminary seal in the absence of a pressure differential without relying on the hatch dogs to p!
rovide
the initial o-ring squeeze.</div>
<div dir="ltr" id="yiv8154287830yui_3_16_0_1_1456935008552_12860">My design entails two o-rings per hatch (vessel has six hatches: cabin loading / escape, outer lockout loading / escape, inner lockout loading / escape, inner lockout egress , outer lockout egress, and transfer). These o-rings are concentric face seals, each residing within a half dovetail groove for positive retention of each o-ring when the hatch is opened or manipulated. The grooves are oriented such that the flat face of each half dovetail faces the intermediate space between the two rings. This intermediate volume is not isolated, but rather connected (on the sealing flange side) to a vacuum transducer, and piped through appropriate valving to a vacuum pump. When the hatch is closed, this intermediate space is pulled to vacuum (as strongly as the pump allows), then locked off, and the strength of this vacuum is measured by the transducer and continuously monitored. The interlock is clear as long as the va!
cuum
holds, a!
nd
activates the moment the seal is rele!
ased,
instead of relying on some arbitrary movement of the hatch to indicate that it is open.</div>
<div dir="ltr" id="yiv8154287830yui_3_16_0_1_1456935008552_12861">Apart from the obvious expense, I see a potential problem with exposing those vacuum transducers in the lockout hatches to high pressure, necessitating either a less sensitive transducer that will withstand the pressure, or some means of isolating the transducer when the pressure approaches the limit of its range - I'm still working this out in my head, but I thought I would share anyway.</div>
<div dir="ltr" id="yiv8154287830yui_3_16_0_1_1456935008552_13102">Sean<br clear="none" />
</div>
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