[PSUBS-MAILIST] Over Pressure Valve
via Personal_Submersibles
personal_submersibles at psubs.org
Thu Jun 18 15:51:21 EDT 2015
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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