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Re: [PSUBS-MAILIST] Bubble of doom
Or a catch hook. At equal pressure you open the hatch - it plops violent open - catch by the hook.
Air bubble rush out - water rush in - but hatch stays open.
vbr Carsten
<vbra676539@aol.com> schrieb:
> A vent valve, perhaps? Just to let the air bubble out. Water from the flood valve lower down would continue to equalize. It would be a nerve wracking wait, though, wouldn't it?
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> -----Original Message-----
> From: Greg Cottrell <greg@precisionplastics.com>
> To: personal_submersibles@psubs.org
> Sent: Fri, Aug 20, 2010 11:01 am
> Subject: [PSUBS-MAILIST] Bubble of doom
>
>
>
> Hi Vance,
>
> You’ve brought up an interestingpoint about the release of air from a sub during egress. George Kittredge had asimilar experience of being “shot out” of a sub (although his subwas full of over pressurized air). I wonder if it might be a good idea to put aflood valve in the hatch to flood a sub completely before getting out?
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>
> Greg Cottrell
> Project Manager
>
>
> greg@precisionplastics.com
> http://www.precisionplastics.com
>
> P please consider the environment before printing this email
>
>
>
> From: owner-personal_submersibles@psubs.org [mailto:owner-personal_submersibles@psubs.org] On Behalf Of vbra676539@aol.com
> Sent: Friday, August 20, 2010 9:25AM
> To: personal_submersibles@psubs.org
> Subject: Re: [PSUBS-MAILIST] Scubatank hook up
>
>
> Alan,
>
>
>
> I must be missing something here. What isthe last 15% of the volume in a flooding scenario? I've never had to do it, butflooding the boat equalizes pressure inside and out. The volume of aircompresses in a high pointto that same pressure. All you would need was a BIBS and a face mask orsomething. No increase of pressure inside would be necessary unless your intentis to maintain a larger air bubble inside the boat, which would be dangerousunless you happened to have a bottom hatch (assuming the boat is in an attitudewhere it could even be used).
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> One caveat about air in the boat that Ido know about is the violence of that bubble's release when the hatch isopened. In the Nekton Beta accident, the bubble shot Rick Slater out of theboat like a cork out of a champagne bottle, and the sudden movement of waterflooding in to replace that air is probably what caused the other passenger tobang his head, which either caused directly or contributed to his drowning atdepth. Based on that, it seems that a larger bubble might very well causeproportionally larger problems.
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> Mind you, flooding the boat is a prettybig problem all by itself. It gives me the shivers just thinking about it.
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> Vance
>
>
> -----OriginalMessage-----
> From: Recon1st@aol.com
> To: personal_submersibles@psubs.org
> Sent: Fri, Aug 20, 2010 8:53 am
> Subject: Re: [PSUBS-MAILIST] Scuba tank hook up
>
> Alan I would not use airto equalize in an emergency. I would simply open my flood
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> valve and let theincoming water do the job. This would allow time to equalize your
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> ears and such. And thevolume of air exploding from the tower is much less violent.
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> Personally I prefer tohave full pressure to the hull and regulate it inside. In all scenarios
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> I can think of, a highflow is not needed. Filling tanks and such, a slow fill seems to be
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> much more controllable.
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> Dean
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> In a message dated 8/19/2010 6:52:01 P.M.Central Daylight Time, alanjames@xtra.co.nzwrites:
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>
> Hi Dean,
>
> I've got more questions than answershere.
>
> If we use air to pressurize the last 15%of the sub volume in an emergency escape,
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> wouldn't it be better to have the fullpressure of the tank coming in through the hull?
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> I googled but couldn't find anything onthe flow rate of air coming straight out of a
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> scuba tank compared to what it might becoming out of a first stage regulator or
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> your 250 psi regulator. ( I guess hosewidth figures in the equation.)
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> I did open up my dive tank into a rubbishbag & it blew it up about 4 x faster straight from
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> the tank at 3000 psi than from the 2ndstage purge valve.
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> In the case of a 200ft deep escape your250 psi regulator would be operating at 150 psi
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> above the ambient pressure required inthe hull to do the final equalization. Having a faster
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> fill might make the difference betweengetting the bends or not.
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> Alan
>
>
>
>
> ----- Original Message -----
>
> From: Recon1st@aol.com
>
> To: personal_submersibles@psubs.org
>
> Sent: Friday, August 20, 2010 6:55 AM
>
> Subject: Re: [PSUBS-MAILIST] Scuba tank hook up
>
>
>
> Sorry for the omission.The Tanks will be external and all I would need is HP. I have
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> regulators inside andthe ability to crank em up to 250 psi. I guess what I am looking for
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> is yoke type with outthe regulator.
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>
> Dean
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>
> In a message dated 8/19/2010 11:26:37A.M. Central Daylight Time, vbra676539@aol.com writes:
>
> External or internal? And are you set upfor high pressure or not? HP air can be had with a simple yoke (like a firststage without the regulator). If you need lower pressure, then the first stagewill work fine. George carried his internally, which was an issue at depthbecause scuba first stages can only be cranked up to about 150-160 pounds.Externally, you get that over ambient, which gives you full flow. The onlyother issue is flow. The 1st stage arrangement is pretty slow.
>
> Vance
>
>
> -----OriginalMessage-----
> From: Recon1st@aol.com
> To: personal_submersibles@psubs.org
> Sent: Thu, Aug 19, 2010 12:03 pm
> Subject: Re: [PSUBS-MAILIST] Scuba tank hook up
>
> What have any of youdone to hook up standard SCUBA tanks for HP air source.
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> Originally I was using alarge steel tank. It is just too heavy to handle and I am
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> switching totwin Aluminum 100 tanks.
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> I am thinking a scubafirst stage regulator is used with an adaptor at the thru hull
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> connection.
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> Appreciate any help
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> Dean
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