[PSUBS-MAILIST] Fwd: Over Pressure Valve

via Personal_Submersibles personal_submersibles at psubs.org
Sun Sep 6 18:37:16 EDT 2015


Brian:  from 6-18-2015
Jim
 
 
  
____________________________________
 From: JimToddPsub at aol.com
To: personal_submersibles at psubs.org
Sent:  6/18/2015 2:51:21 P.M. Central Daylight Time
Subj: Over Pressure  Valve


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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