<div dir="ltr">If it opens when submerged, it is because air is on the way out, and that prevents water from coming in. Its like blowing through your nose underwater, your nose is open but if you're blowing, you don't get water in your lungs.<div><br></div><div>Certainly you do get a little water in if you push the valve open manually while submerged, as a test. Or a few drops if you do so when surfaced to equalize, as the valve is all wet. But its nothing much.</div><div><br></div><div><br><div>Best,<br><br>Alec</div></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Thu, Jun 18, 2015 at 7:19 PM, Ken Martindale via Personal_Submersibles <span dir="ltr"><<a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">TEST!!!<br>
<br>
-----Original Message-----<br>
From: Personal_Submersibles [mailto:<a href="mailto:personal_submersibles-bounces@psubs.org">personal_submersibles-bounces@psubs.org</a>] On Behalf Of via Personal_Submersibles<br>
Sent: Thursday, June 18, 2015 4:28 PM<br>
To: Personal Submersibles General Discussion<br>
Subject: Re: [PSUBS-MAILIST] Over Pressure Valve<br>
<br>
How do you keep water from going back down the valve, and into the sub, if it opens when submerged?<br>
<br>
Keith T<br>
<br>
via Personal_Submersibles <<a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>> wrote:<br>
<br>
>If the pressure differential exceeds the preset cracking  pressure, the<br>
>valve will open on its own to relieve the excess pressure.   If the pressure<br>
>differential is less than the cracking pressure, it would have  to be<br>
>opened manually.  If the differential were only slightly greater than<br>
>the preset cracking pressure, I suppose opening it manually would open<br>
>it wider for more rapid equalization on many types of valves.<br>
>Jim<br>
><br>
><br>
>In a message dated 6/18/2015 2:40:58 P.M. Central Daylight Time,<br>
><a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a> writes:<br>
><br>
><br>
>Jim,<br>
>           In that case  is it necessary to bump the sealed check valve<br>
>to make it open?<br>
><br>
><br>
>Alec,  I guess what I meant to say was if the check valve is left in<br>
>an open line to the outside all the time, rather than being isolated by<br>
>another valve.<br>
><br>
>Brian<br>
><br>
>--- <a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>  wrote:<br>
><br>
>From: via Personal_Submersibles  <<a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>><br>
>To:  <a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a><br>
>Subject: Re: [PSUBS-MAILIST]  Idea..?<br>
>Date: Thu, 18 Jun 2015 14:53:15 -0400<br>
><br>
><br>
><br>
>Brian, it also has to do with cracking pressure.  When  you surface the<br>
>sub might be slightly over pressure but not with enough  differential<br>
>to open the valve automatically.  That's when you open it  manually.<br>
>That would also equalize pressure if you have negative  pressure in the<br>
>sub to make it a whole lot easier to open the  hatch.<br>
>Jim<br>
><br>
><br>
>In a message dated 6/18/2015 1:40:32 P.M. Central Daylight Time,<br>
><a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a> writes:<br>
><br>
>It is nothing but a T shape sealed by a spring. If internal  pressure<br>
>builds up, it pushes the spring and the valve opens. So it is a<br>
>normally closed valve... but I suppose you could say its "open all the<br>
>time"  in the sense that anytime pressure builds up, it will open.<br>
><br>
>On Thu, Jun 18, 2015 at 2:35 PM, Brian Cox via Personal_Submersibles<br>
><_personal_submersibles@psubs.org_<br>
>(mailto:<a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>) ><br>
>wrote:<br>
><br>
><br>
>Couldn't you, theoretically,  have that valve open to the  outside all the<br>
>time?<br>
><br>
>Brian<br>
><br>
>--- _personal_submersibles@psubs.org_<br>
>(mailto:<a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>)   wrote:<br>
><br>
>From: Alec Smyth via Personal_Submersibles<br>
><_personal_submersibles@psubs.org_<br>
>(mailto:<a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>) ><br>
>To:  Personal Submersibles General Discussion<br>
><_personal_submersibles@psubs.org_<br>
>(mailto:<a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>) ><br>
>Subject:  Re: [PSUBS-MAILIST] Idea..?<br>
>Date: Thu, 18 Jun 2015 12:15:57  -0400<br>
><br>
><br>
><br>
><br>
>I think most have an OP valve, and I'd strongly encourage any  who<br>
>don't to put one in. If you read Kittredge's book, the lack of an OP<br>
>valve was the cause of the only K-boat accident so far. Fortunately<br>
>nothing happened to him, but Kittredge had a slow cabin air leak during<br>
>his dive and upon surfacing blew out the dome when just below the<br>
>surface.  He was blown out himself with it. The sub sank, and he<br>
>proceeded to  re-float it without losing beat. I use the OP valve<br>
>routinely to  equalize pressure so I can open the hatch easily. Just a<br>
>little push on  the stem does it. One thing about OP valves, they have<br>
>to be capable of  handling large flow rates. Don't use a little Swagelok check valve or such  small thing.<br>
><br>
><br>
>Best,<br>
><br>
>Alec<br>
><br>
><br>
><br>
><br>
><br>
><br>
><br>
>On Thu, Jun 18, 2015 at 10:55 AM, Brian Cox via Personal_Submersibles<br>
><_personal_submersibles@psubs.org_<br>
>(mailto:<a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>) ><br>
>wrote:<br>
><br>
>Also  Alec,   I noticed your check valve overpressure valve in the  photo<br>
>section.  That seems like a great solution to the  problem!   I guess I was<br>
>not aware of that, does everybody  have one of those?<br>
><br>
><br>
>Brian<br>
><br>
>--- _personal_submersibles@psubs.org_<br>
>(mailto:<a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>)   wrote:<br>
><br>
>From: hank pronk via Personal_Submersibles<br>
><_personal_submersibles@psubs.org_<br>
>(mailto:<a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>) ><br>
>To:  Personal Submersibles General Discussion<br>
><_personal_submersibles@psubs.org_<br>
>(mailto:<a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>) ><br>
>Subject:  Re: [PSUBS-MAILIST] Idea..?<br>
>Date: Thu, 18 Jun 2015 05:25:30  -0700<br>
><br>
><br>
><br>
>personally, I always avoid welding a machined part to the  hull.  I<br>
>weld a flange or nipple to the hull then bolt or thread  the machined part to that.<br>
> This is my solution to a lack of  tooling and expertise.<br>
>Hank  --------------------------------------------<br>
>On Thu, 6/18/15, James  Frankland via Personal_Submersibles<br>
><_personal_submersibles@psubs.org_ (mailto:<a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>) >  wrote:<br>
><br>
>Subject: Re: [PSUBS-MAILIST] Idea..?<br>
>To:  "Personal Submersibles General Discussion"<br>
><_personal_submersibles@psubs.org_<br>
>(mailto:<a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>) ><br>
>Received:  Thursday, June 18, 2015, 4:58  AM<br>
><br>
>Hi<br>
>Alec\Brian, Yes, maybe it  would<br>
>push in.  A flat step would probably be better like  you<br>
>say.  But maybe im over thinking it as usual.   Probably<br>
>not required. Brian, I used the<br>
>5\8ths  bar because that's what was specified on the<br>
>plans.   However, its also convenient for using a 16mm<br>
>reamer for the  bore.<br>
>regardsJames<br>
>On 18 June 2015  at 03:04,<br>
>Brian Cox via Personal_Submersibles <_personal_submersibles@psubs.org_<br>
>(mailto:<a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>) ><br>
>wrote:<br>
>Oh  cool !   Thanks Alec<br>
>!    I owe you  much over the years<br>
>! Brian<br>
>--- _personal_submersibles@psubs.org_<br>
>(mailto:<a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>)<br>
>wrote:<br>
><br>
>From:  Alec Smyth via<br>
>Personal_Submersibles <_personal_submersibles@psubs.org_<br>
>(mailto:<a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>) ><br>
>To:  Personal Submersibles General Discussion<br>
><_personal_submersibles@psubs.org_<br>
>(mailto:<a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>)<br>
>><br>
>Subject:  Re: [PSUBS-MAILIST] Idea..?<br>
>Date: Wed, 17 Jun 2015 16:40:56  -0400<br>
><br>
>Hi Brian,<br>
>I tend to use quite  thick<br>
>through-hulls because its easier for me to machine  the O-ring grooves<br>
>into the shaft than into the insert. In  my case its just a matter of<br>
>the tooling I have on hand. If  you have the tooling to put the grooves<br>
>in the insert, half  an inch is fine for many  applications.<br>
>Best,<br>
><br>
>Alec<br>
>On<br>
>Wed,  Jun 17, 2015 at 3:22 PM, Brian Cox via Personal_Submersibles<br>
><_personal_submersibles@psubs.org_<br>
>(mailto:<a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>) ><br>
>wrote:<br>
>Alec,  James,  I'm<br>
>using mostly 1/2" stainless rod through-out  for most all of my hull<br>
>penetrations ( for valves and  flaps) ,  I noticed in the example it<br>
>was a 5/8" rod,  Why such a heavy duty thickness?  Was that for a<br>
>particular function? Brian<br>
><br>
>--- _personal_submersibles@psubs.org_<br>
>(mailto:<a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>)<br>
>wrote:<br>
><br>
>From:  Alec Smyth via<br>
>Personal_Submersibles <_personal_submersibles@psubs.org_<br>
>(mailto:<a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>) ><br>
>To:  Personal Submersibles General Discussion<br>
><_personal_submersibles@psubs.org_<br>
>(mailto:<a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>)<br>
>><br>
>Subject:  Re: [PSUBS-MAILIST] Idea..?<br>
>Date: Wed, 17 Jun 2015 14:03:17  -0400<br>
><br>
>Hi James,<br>
>I think<br>
>with the taper,  this would tend to push in and jam. The idea is neat,<br>
>however,  and would probably work fine with a step instead of a taper.<br>
>On  the other hand, does an O ring sealed through-hull ever fail<br>
>catastrophically? I've had the odd drip, but that's all I've  bad as<br>
>I've seen.<br>
>Best,<br>
>Alec<br>
>On<br>
>Wed,  Jun 17, 2015 at 12:26 PM, James Frankland  via<br>
>Personal_Submersibles <_personal_submersibles@psubs.org_<br>
>(mailto:<a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>) ><br>
>wrote:<br>
>Hi  All Seeing as its a<br>
>bit quite I thought I would show this  idea.  Its super simple.... I<br>
>have been thinking  how you could stop a leaking through hull.<br>
>Thinking of K  boat type 5\8th through hulls as in the plans. I<br>
>believe Scott had a leak when he did his deep test due to a  faulty O<br>
>ring?<br>
><br>
>Anyway, here is my idea.   It<br>
>would take a little bit more machining, but not  much.<br>
>Machine the 5\8ths bar with a taper on the  protruding part and a taper<br>
>on the top to help push the bar  through.<br>
>(I did that on mine anyway).  The handle is  made with a cam type end.<br>
><br>
>If you get  a<br>
>leak, you can pull the handle up.  The bar would be  pulled up, forcing<br>
>the taper to jam into the penetrator,  hopefully stopping most of the<br>
>leak.  I suppose you could  even machine a matching taper into the<br>
>start of the through  hull to match? I suppose the bar could get pushed<br>
>through and jam on its own.  That's  a possibility. Pic attached. Kind<br>
>RegardsJames ​<br>
><br>
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><a href="http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles" rel="noreferrer" target="_blank">http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles</a><br>
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><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" rel="noreferrer" target="_blank">http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles</a><br>
<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" rel="noreferrer" target="_blank">http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles</a><br>
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<br>
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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" rel="noreferrer" target="_blank">http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles</a><br>
</blockquote></div><br></div>