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

Thu Dec 12 14:06:00 EST 2013

Jim an AOP opens only under water in a over pressure situation. 
Means air rush out but nearly no water in. 
On the surface you just push the button on the valve below the spring and you equalize the rest. 
Sgt.Peppers has such a valve and Eurosub/Javasub/Nordicsub also.
Some other sub has simillar design valve.  And no problems with a hatch flying. 
Sometime with a to low spring load they leak a drop- so what? 
On Peppers the push button below the spring is formed as small cup.. 

A manual vale like a ball vale can be only open on the surface - means you can create 
a heavy overpressure load on the latches. 

On Euronaut we had only a manual ball valve and a overpressure situation because of a heavy air leak (a human turns the wrong air valve and over pressure the cabin. 
We decide to open the manual ball valve during the ascent to prevent a overload on the latches and the operator under the valve get very wet before we reach the surface. 

If you view you atmostpheric gauge (barometer or aircraft altimeter) time by time and you have a compressor you can equalize also with that the overpressure. On Euronaut we have two compressor which can handle hundreds of liter per minutes to equalize or even create a vaccum. Unfortune on that day nobody turns the aircraft altimeter to zero - so we had no information what equalize means and we decide to open the ball valve underwater manual. 

I now at least two submarines in psub sizes which had serious problems with cabin over pressure. In one the hatch/dome plopps open in 2 feet water depth but lucky the hatch/dome close again. The pilot got very wet - thats all. In the other boat the hatch/dome plopps open in 3 feet of water and stays open. The boat sunk. One crew under the hatch manage get out immedatly the other with iron balls  (and thousands of hours as diver) stays in the wreck and climp out after the boat hit the ground in 28 feet depth. The boat was later salvage but all electronics and electric was complete destroyed.. 

vbr Carsten

<jimtoddpsub at aol.com> schrieb: 
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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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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