[PSUBS-MAILIST] Hatch Closure Mechanism

[Alan via Personal_Submersibles]

River,
GL also requires an over-pressure valve so I think this is in addition to that.
As Steve pointed out, if the closing spring on the over-pressure valve is 
2psi then that is 620 lb. pressure (Steve makes it 1000kg) that the hatch
will still be seeing.
Wonder if Vance has any experience on this?
Alan


Sent from my iPad

> On 31/12/2017, at 5:52 PM, River Dolfi via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> Ooops, ignore that previous rule. I was reading the Lloyds of London rules, not German Lloyds.
> 
> "2.1
> The access and exit hatches shall be provided with a closing mechanism which makes it possible to create, even when the submersible is surfaced, a sufficient contact force on the hatch sealing. Sealing systems for hatch covers shall be approved by the Society.
> In addition the closing mechanism shall be designed in a way that opening of the hatch is only possible after pressure equalization has happened, see [4]."
> 
> Of course, now that I think about it, this requirement is redundant. If an overpressure valve is installed, there would never be high pressure in the cabin to need to relieve. If there is an underpressure, you wouldn't be able to open the hatch anyway!
> 
> Thanks,
> 
> -River J. Dolfi
> rdolfi7 at gmail.com
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