[PSUBS-MAILIST] Over Pressure Valve
via Personal_Submersibles
personal_submersibles at psubs.org
Thu Jun 18 16:27:41 EDT 2015
How do you keep water from going back down the valve, and into the sub, if it opens when submerged?
Keith T
via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>If the pressure differential exceeds the preset cracking pressure, the
>valve will open on its own to relieve the excess pressure. If the pressure
>differential is less than the cracking pressure, it would have to be opened
>manually. If the differential were only slightly greater than the preset
>cracking pressure, I suppose opening it manually would open it wider for more
>rapid equalization on many types of valves.
>Jim
>
>
>In a message dated 6/18/2015 2:40:58 P.M. Central Daylight Time,
>personal_submersibles at psubs.org writes:
>
>
>Jim,
> In that case is it necessary to bump the sealed check valve to
>make it open?
>
>
>Alec, I guess what I meant to say was if the check valve is left in an
>open line to the outside all the time, rather than being isolated by another
>valve.
>
>Brian
>
>--- personal_submersibles at psubs.org wrote:
>
>From: via Personal_Submersibles <personal_submersibles at psubs.org>
>To: personal_submersibles at psubs.org
>Subject: Re: [PSUBS-MAILIST] Idea..?
>Date: Thu, 18 Jun 2015 14:53:15 -0400
>
>
>
>Brian, it also has to do with cracking pressure. When you surface the sub
>might be slightly over pressure but not with enough differential to open
>the valve automatically. That's when you open it manually. That would also
>equalize pressure if you have negative pressure in the sub to make it a
>whole lot easier to open the hatch.
>Jim
>
>
>In a message dated 6/18/2015 1:40:32 P.M. Central Daylight Time,
>personal_submersibles at psubs.org writes:
>
>It is nothing but a T shape sealed by a spring. If internal pressure
>builds up, it pushes the spring and the valve opens. So it is a normally closed
>valve... but I suppose you could say its "open all the time" in the sense
>that anytime pressure builds up, it will open.
>
>On Thu, Jun 18, 2015 at 2:35 PM, Brian Cox via Personal_Submersibles
><_personal_submersibles at psubs.org_ (mailto:personal_submersibles at psubs.org) >
>wrote:
>
>
>Couldn't you, theoretically, have that valve open to the outside all the
>time?
>
>Brian
>
>--- _personal_submersibles at psubs.org_
>(mailto:personal_submersibles at psubs.org) wrote:
>
>From: Alec Smyth via Personal_Submersibles
><_personal_submersibles at psubs.org_ (mailto:personal_submersibles at psubs.org) >
>To: Personal Submersibles General Discussion
><_personal_submersibles at psubs.org_ (mailto:personal_submersibles at psubs.org) >
>Subject: Re: [PSUBS-MAILIST] Idea..?
>Date: Thu, 18 Jun 2015 12:15:57 -0400
>
>
>
>
>I think most have an OP valve, and I'd strongly encourage any who don't to
>put one in. If you read Kittredge's book, the lack of an OP valve was the
>cause of the only K-boat accident so far. Fortunately nothing happened to
>him, but Kittredge had a slow cabin air leak during his dive and upon
>surfacing blew out the dome when just below the surface. He was blown out himself
>with it. The sub sank, and he proceeded to re-float it without losing
>beat. I use the OP valve routinely to equalize pressure so I can open the
>hatch easily. Just a little push on the stem does it. One thing about OP
>valves, they have to be capable of handling large flow rates. Don't use a little
>Swagelok check valve or such small thing.
>
>
>Best,
>
>Alec
>
>
>
>
>
>
>
>On Thu, Jun 18, 2015 at 10:55 AM, Brian Cox via Personal_Submersibles
><_personal_submersibles at psubs.org_ (mailto:personal_submersibles at psubs.org) >
>wrote:
>
>Also Alec, I noticed your check valve overpressure valve in the photo
>section. That seems like a great solution to the problem! I guess I was
>not aware of that, does everybody have one of those?
>
>
>Brian
>
>--- _personal_submersibles at psubs.org_
>(mailto:personal_submersibles at psubs.org) wrote:
>
>From: hank pronk via Personal_Submersibles
><_personal_submersibles at psubs.org_ (mailto:personal_submersibles at psubs.org) >
>To: Personal Submersibles General Discussion
><_personal_submersibles at psubs.org_ (mailto:personal_submersibles at psubs.org) >
>Subject: Re: [PSUBS-MAILIST] Idea..?
>Date: Thu, 18 Jun 2015 05:25:30 -0700
>
>
>
>personally, I always avoid welding a machined part to the hull. I weld a
>flange or nipple to the hull then bolt or thread the machined part to that.
> This is my solution to a lack of tooling and expertise.
>Hank --------------------------------------------
>On Thu, 6/18/15, James Frankland via Personal_Submersibles
><_personal_submersibles at psubs.org_ (mailto:personal_submersibles at psubs.org) > wrote:
>
>Subject: Re: [PSUBS-MAILIST] Idea..?
>To: "Personal Submersibles General Discussion"
><_personal_submersibles at psubs.org_ (mailto:personal_submersibles at psubs.org) >
>Received: Thursday, June 18, 2015, 4:58 AM
>
>Hi
>Alec\Brian, Yes, maybe it would
>push in. A flat step would probably be better like you
>say. But maybe im over thinking it as usual. Probably
>not required. Brian, I used the
>5\8ths bar because that's what was specified on the
>plans. However, its also convenient for using a 16mm
>reamer for the bore.
>regardsJames
>On 18 June 2015 at 03:04,
>Brian Cox via Personal_Submersibles <_personal_submersibles at psubs.org_
>(mailto:personal_submersibles at psubs.org) >
>wrote:
>Oh cool ! Thanks Alec
>! I owe you much over the years
>! Brian
>--- _personal_submersibles at psubs.org_
>(mailto:personal_submersibles at psubs.org)
>wrote:
>
>From: Alec Smyth via
>Personal_Submersibles <_personal_submersibles at psubs.org_
>(mailto:personal_submersibles at psubs.org) >
>To: Personal Submersibles General Discussion
><_personal_submersibles at psubs.org_ (mailto:personal_submersibles at psubs.org)
>>
>Subject: Re: [PSUBS-MAILIST] Idea..?
>Date: Wed, 17 Jun 2015 16:40:56 -0400
>
>Hi Brian,
>I tend to use quite thick
>through-hulls because its easier for me to machine the
>O-ring grooves into the shaft than into the insert. In my
>case its just a matter of the tooling I have on hand. If you
>have the tooling to put the grooves in the insert, half an
>inch is fine for many applications.
>Best,
>
>Alec
>On
>Wed, Jun 17, 2015 at 3:22 PM, Brian Cox via
>Personal_Submersibles <_personal_submersibles at psubs.org_
>(mailto:personal_submersibles at psubs.org) >
>wrote:
>Alec, James, I'm
>using mostly 1/2" stainless rod through-out for most
>all of my hull penetrations ( for valves and flaps) , I
>noticed in the example it was a 5/8" rod, Why such a
>heavy duty thickness? Was that for a particular
>function? Brian
>
>--- _personal_submersibles at psubs.org_
>(mailto:personal_submersibles at psubs.org)
>wrote:
>
>From: Alec Smyth via
>Personal_Submersibles <_personal_submersibles at psubs.org_
>(mailto:personal_submersibles at psubs.org) >
>To: Personal Submersibles General Discussion
><_personal_submersibles at psubs.org_ (mailto:personal_submersibles at psubs.org)
>>
>Subject: Re: [PSUBS-MAILIST] Idea..?
>Date: Wed, 17 Jun 2015 14:03:17 -0400
>
>Hi James,
>I think
>with the taper, this would tend to push in and jam. The idea
>is neat, however, and would probably work fine with a step
>instead of a taper. On the other hand, does an O ring sealed
>through-hull ever fail catastrophically? I've had the
>odd drip, but that's all I've bad as I've
>seen.
>Best,
>Alec
>On
>Wed, Jun 17, 2015 at 12:26 PM, James Frankland via
>Personal_Submersibles <_personal_submersibles at psubs.org_
>(mailto:personal_submersibles at psubs.org) >
>wrote:
>Hi All Seeing as its a
>bit quite I thought I would show this idea. Its super
>simple.... I have been thinking how
>you could stop a leaking through hull. Thinking of K boat
>type 5\8th through hulls as in the
>plans. I believe Scott had a leak
>when he did his deep test due to a faulty O ring?
>
>Anyway, here is my idea. It
>would take a little bit more machining, but not much.
>Machine the 5\8ths bar with a taper on the protruding
>part and a taper on the top to help push the bar through.
>(I did that on mine anyway). The handle is made with a cam
>type end.
>
>If you get a
>leak, you can pull the handle up. The bar would be pulled
>up, forcing the taper to jam into the penetrator, hopefully
>stopping most of the leak. I suppose you could even
>machine a matching taper into the start of the through hull
>to match? I suppose the bar could get
>pushed through and jam on its own. That's a
>possibility. Pic
>attached. Kind
>RegardsJames
>
>
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