[PSUBS-MAILIST] Life Support Alarms

[Alan via Personal_Submersibles]

Hi Alec,
I'm behind in my emails here, but I would guess that most of your bow
dome would be under water when you surfaced, still undergoing an external
water pressure that decreases towards the surface. 
That would be countering the internal pressure to an extent, so maybe not so
much of a worry as a hatch dome.
Alan


> On 14/12/2020, at 12:40 PM, Alec Smyth via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> 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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> <Pressure Gauge Faceplate resized no border.jpg>
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