[PSUBS-MAILIST] Over Pressure Valve

via Personal_Submersibles personal_submersibles at psubs.org
Fri Jun 19 03:07:12 EDT 2015


Jim,

Thanks for the mental diagram, that helps imensely. Does any one know how the big boys, navy subs, deal with over pressure? Has any one had their OP valve open at depth and if so how much water came in?

Keith T

via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

>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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