[PSUBS-MAILIST] G.L. summary Pressure Hull

Wed Dec 11 22:45:31 EST 2013

Hi Alan,

There isn't much distance between the water line and the top of the hull especially if you consider a little roll and  wave action.  I've wondered how much seepage you would get if the AOP opened under water in response to OP.   Since the flow would be outward I'm hoping it wouldn't be much.  Those people who already have functioning AOPs could speak better than I can regarding water entry when surfaced.  I'm hoping the water sheds nearly completely on the outside.  If your design uses a conning tower, you could possibly mount it horizontally near the top if necessary.  I'm getting into guessing now in the absence of having an AOP and penetrator in my hand to play with. 

I'm hoping the only experience I ever have with underwater operation of an AOP valve is with a test chamber I can build and pressurize.  Won't be anytime soon.

Good luck!
Jim

-----Original Message-----
From: Alan James <alanlindsayjames at yahoo.com>
To: Personal Submersibles General Discussion <personal_submersibles at psubs.org>
Sent: Wed, Dec 11, 2013 8:56 pm
Subject: Re: [PSUBS-MAILIST] G.L. summary Pressure Hull

Hi Jim,
If you placed the through hull for the AOP valve on the hull wall above the water line 
when surfaced, but not on the roof of the sub, then you could mount the AOP 
above the hull stop safety valve. This would eliminate the small amount of water 
that does sit in the AOP valve when roof mounted, from coming in.
I haven't got to it yet in G.L. but there is bound to be some sort of over-pressure 
alarm requirement which would alert you to surface slowly.
   I am thinking along the lines of a cam wheel on the hatch closure mechanism that 
plunges the AOP  valve stem when rotated slightly & comes off again when closed.
Regards Alan

   From: "jimtoddpsub at aol.com" <jimtoddpsub at aol.com>
 To: personal_submersibles at psubs.org 
 Sent: Thursday, December 12, 2013 3:30 PM
 Subject: Re: [PSUBS-MAILIST] G.L. summary Pressure Hull

Alan,

Right, the AOP would not be accessible the way I described.  Under-pressure would have to be addressed as Vance described.  As long as the differential pressure is minimal in either direction you can equalize it on the surface.  Hopefully that would always be the situation.  For equalizing on the surface I don't know that it makes much difference whether your valve is manual or automatic.  However if you have a significant OP situation while submerged (say 3 psi or greater) either unrecognized or unresolvable, you could have a ton of pressure on the hatch before you reach the surface.  We'll never know how much OP Capt. Kitteredge encountered when he suddenly found himself outside the sub with the sub sinking.  Whatever that amount was he wasn't aware that it even existed.

If the AOP is installed below the manual valve, then you will admit water into the line if you open it when submerged.  If you only open it on the surface, the only reason I can see for having an automatic instead of a manual is in case you forget to open it.  There certainly could be some other consideration I'm missing.

Jim

-----Original Message-----
From: Alan James <alanlindsayjames at yahoo.com>
To: Personal Submersibles General Discussion <personal_submersibles at psubs.org>
Sent: Wed, Dec 11, 2013 7:47 pm
Subject: Re: [PSUBS-MAILIST] G.L. summary Pressure Hull

Hi Jim,
I don't think we are on the same page.
The automatic over-pressure valve wouldn't be regarded as a pressure
equalizing valve by G.L. as it would only take the internal pressure down 
to what it's setting was, & wouldn't equalize a negative pressure situation.
Emile's AOP valve & others I have seen have a plunger you can push to
fully equalize positive or negative pressure. So you would need to have 
the AOP after the emergency closure valve to be able to manually operate it. 
The emergency closure valve would have to be open all the time, but would
have no bearing on the state of pressure equalization beyond what the
AOP would achieve. 
Alan

   From: "jimtoddpsub at aol.com" <jimtoddpsub at aol.com>
 To: personal_submersibles at psubs.org 
 Sent: Thursday, December 12, 2013 1:49 PM
 Subject: Re: [PSUBS-MAILIST] G.L. summary Pressure Hull

Alan,

Most likely you would be diving with the manual valve open.  In fact you could leave it open all the time.  The AOP does the work; the manual valve is just there as a shut off if the AOP leaks, and the handle position requires that it has to be open before you could unlatch.  As long as the valve is open, the handle isn't in the way at all.  Depending on the latch design, the valve handle may or may not have to be in the open position to latch it as well.  

If you only have a manual valve and no AOP you have a completely different situation.  I wouldn't want to have that setup.

Jim

-----Original Message-----
From: Alan James <alanlindsayjames at yahoo.com>
To: Personal Submersibles General Discussion <personal_submersibles at psubs.org>
Sent: Wed, Dec 11, 2013 4:47 pm
Subject: Re: [PSUBS-MAILIST] G.L. summary Pressure Hull

If you have an over-pressure valve handle obstructing the 
movement of the hatch latch handle, it would need to be
spring loaded or you would create the problem of the possibility
of diving with the valve open later on.
With the G.L. qualification I mentioned of having 2 shut off valves,
I guess you could put the shut off valve at the hull & the over-pressure 
valve anywhere on a line coming from it, & use it additionally as the 
equalization valve. Possibly then place the over-pressure valve some how
 that it could be plunged as the latch handle was moved.
Alan

   From: "MerlinSub at t-online.de" <MerlinSub at t-online.de>
 To: Personal Submersibles General Discussion <personal_submersibles at psubs.org> 
 Sent: Thursday, December 12, 2013 11:05 AM
 Subject: Re: [PSUBS-MAILIST] G.L. summary Pressure Hull

I am pretty sure GL and the other classes like a hatch, OP, AOP solution
without electronics a lot more.   

On Euronaut there is a manual ballvale as Overpressure valve integrate in the hatch
and a red label on the hatch handle "Never open before equalize". 

Its not with the rule because we assume the operator is able to read a red label - but for us it works. 

 In case I had to build something with the rules I just will block with the ballvalve handle in close position 
the hatch handle or the latches. 

Another way could be to design the hatch latches that way on a tread handle 
that you have to turn the whell some turns and it gives the hatches only a litte opening  to equalize 
and gives the latches later complete free with more turns. 
In that way you can open the hatch very fast in case in the batterey get very hot below your feets.. 
And you can still blow your ears drums away in case you like that.. 

vbr Carsten

"Jon Wallace" <jonw at psubs.org> schrieb:

      Advantage: ABS

      I think the sentence being scrutinized may perhaps just be badly      worded.  With the exception of some intricate mechanism that      equalizes as part of a sequence to open the hatch as Jim      suggested, I don't see a way to comply with the requirement      without the involvement of electronics.  Philosophically I don't      think I want to rely on an electromagnet or boolean logic giving      me permission to exit the vessel.  If Jim's mechanism turns out to      be to complicated then Doug's concern is valid...remember Apollo      1.

      Jon

      On 12/11/2013 4:17 PM, Alan James wrote:

Hi Doug,

Elaborating on your            idea.

If you had digital            pressure gauges you could have a system

comparing the voltage            of the two, & when they were in a 

similar range they            would activate or deactivate an electromagnet

that pulled back a            latch that was impeding the movement of the hatch

release mechanism.            (car door lock mechanism) You would

need a manual            over-ride. Any electronics nerd could do this easily

& the car lock            mechanisms I've seen for round $20-

With the            over-pressure valve set at a couple of psi you know

that on the surface            the most over pressure there could be is

what your            over-pressure valve is set at. Under-pressure is

not such an issue as            you won't be able to physically open the hatch 

if the under pressure            is too much, & hence you have to equalize.

So I don't think it            needs sophisticated monitoring. 

I'm not sure how much            of an issue it would be if you opened your

hatch with a couple of            psi over-pressure. Would the dome fly

open at 90 miles an            hour, or would pressure be released incrementally

as the hatch dogs            unlatched before fully releasing.

Obviously G.L. thinks            this is an issue.

Alan

-- 

Carsten Standfuß
Dipl.Ing.Schiffbau @ Meerestechnik
Heinrich Reck Str.12A
18211 Admannshagen Germany

+49 (0) 172 8464 420
WWW.Euronaut.org
Carsten at euronaut.org

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