[PSUBS-MAILIST] Life Support Alarms

[Alec Smyth via Personal_Submersibles]

Hi Jon,

Ah, the one that needs discussion in my opinion is the internal pressure.
For every 1psi of internal over-pressure, my bow dome sees 566 lbs of force
trying to blow it out of the sub (at the surface of course.) How much can
it take before blowing out? I don't know, and it's not something I can
test. The highest I've ever gone I think is 0.5psi over ambient. On the
negative side, there's no problem of course and one could go to a much
higher value with no problem. Internal pressure is the reason an
overpressure valve is essential, but there again I'm running a little by
the seat of my pants at the moment because although I have a large OP
valve, I don't know its cracking pressure. Cliff, however, is coming to the
rescue soon because he is planning to actually measure this. More to follow
sometime soon...

Note the color coding thresholds on my cabin pressure faceplate (attached.)
They are not scientific, however, and the thresholds would in any case be
dependent on construction details of each sub.


Best,
Alec



On Sun, Dec 13, 2020 at 12:43 PM Jon Wallace via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

> I'm looking to start a discussion to create a PSUBS standard for max/min
> cabin operating conditions.  I'm not convinced temp or humidity matter all
> that much overall and require an agreement.  I would start with the
> following:
>
> O2:    19.0 to 23 percent
> CO2:  0 to 5000 ppm
> Pressure:  +/- 1psi
>
> Comments?
> _______________________________________________
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> Personal_Submersibles at psubs.org
> http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
>
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