[PSUBS-MAILIST] Life Support Alarms

[Sean T. Stevenson via Personal_Submersibles]

One final thought regarding the carbon dioxide measurement: by all means, try to bring it down as close to zero as is possible during a dive, but remember that atmospheric air has ~414 ppm CO2 in it, so it might be worth linking your scrubber fan circuit to a hatch interlock, (or setting a low cutoff value) so that you don't needlessly run the scrubber fan while the hatch is open on the surface chasing a CO2 target that you can't achieve.

I would also be inclined to set both warning and alarm limits for all parameters, the alarms being the permitted minimums / maximums, and the warnings being an early indication to draw your attention to a parameter approaching an alarm limit while still providing sufficient time to take corrective action.

Sean

-------- Original Message --------
On Dec. 13, 2020, 10:42, Jon Wallace via Personal_Submersibles 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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