[PSUBS-MAILIST] Over Pressure Valve
via Personal_Submersibles
personal_submersibles at psubs.org
Fri Jun 19 00:24:19 EDT 2015
Keith,
Sorry, I just got home. I was hoping Alec and some others with more
experience than I have would chime in as I see has now happened. There have
been some good discussions on OP valves in the past. I think some have
installed a T (on its side) inside the sub so the air enters the horizontal
portion, and any water that comes in goes down to a small trap or into a tube
that leads to a reservoir. Others just use a rag to catch the small amount
of water.
Alec, does the OP on the exterior of Snoopy point downward after it exits
at the top?
We've also discussed having an air pressure gauge or altimeter set to zero
(1 atm) before diving. If it indicates any pressure above that level at
anytime during your dive, you'll know you'll have an over pressure situation
to deal with as you surface and you'll have an indication of how severe
that will be. We've also discussed various things that could cause an over
pressure condition.
Best regards,
Jim
In a message dated 6/18/2015 7:09:19 P.M. Central Daylight Time,
personal_submersibles at psubs.org writes:
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.
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.
Best,
Alec
On Thu, Jun 18, 2015 at 7:19 PM, Ken Martindale via Personal_Submersibles
<_personal_submersibles at psubs.org_ (mailto:personal_submersibles at psubs.org)
> wrote:
TEST!!!
-----Original Message-----
From: Personal_Submersibles
[mailto:_personal_submersibles-bounces at psubs.org_ (mailto:personal_submersibles-bounces at psubs.org) ] On Behalf Of via
Personal_Submersibles
Sent: Thursday, June 18, 2015 4:28 PM
To: Personal Submersibles General Discussion
Subject: Re: [PSUBS-MAILIST] Over Pressure Valve
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_
(mailto: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_ (mailto: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_
(mailto:personal_submersibles at psubs.org) wrote:
>
>From: via Personal_Submersibles <_personal_submersibles at psubs.org_
(mailto:personal_submersibles at psubs.org) >
>To: _personal_submersibles at psubs.org_
(mailto: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_ (mailto: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_
(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_
(mailto:personal_submersibles at psubs.org) ) wrote:
>
>From: Alec Smyth via Personal_Submersibles
><_personal_submersibles at psubs.org_
>(mailto:_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_
(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_
(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_
(mailto:personal_submersibles at psubs.org) ) wrote:
>
>From: hank pronk via Personal_Submersibles
><_personal_submersibles at psubs.org_
>(mailto:_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_
(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_ (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_
(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_
(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_
(mailto:personal_submersibles at psubs.org) )
>wrote:
>
>From: Alec Smyth via
>Personal_Submersibles <_personal_submersibles at psubs.org_
>(mailto:_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_
(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_
(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_
(mailto:personal_submersibles at psubs.org) )
>wrote:
>
>From: Alec Smyth via
>Personal_Submersibles <_personal_submersibles at psubs.org_
>(mailto:_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_
(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_
(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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