[PSUBS-MAILIST] Acceptable cabin pressure swing

[Alec Smyth via Personal_Submersibles]

That is an interesting question, but I come in way lower than the values
you're suggesting. On Snoopy I set the red-line on the cabin pressure gauge
at 1/2 psi. The force on the hatch at the surface, with an overpressure of
1/2 psi, would be close to 400 lbs. I'm not sure what pressure the hatch
would blow at, and of course I did have an over-pressure valve, but with
the big acrylic dome held down by some UHMW tabs I would not be comfortable
with any more than that. For what it's worth (and for Doug's peace of
mind!) I did in fact take it to 1/2 psi without it blowing so know its good
at least to that threshold. My limit might sound like the cabin pressure
has to be awfully closely dialed in, but in practice it's not something I
found had any tendency toward wild swings, and could be easily kept under
that threshold with a tweak of the O2 feed every 20 minutes or so.

Best,

Alec

On Wed, Feb 24, 2016 at 2:12 PM, Jon Wallace via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

>
> I think this is somewhat subjective but what is general consensus on
> maximum cabin pressure swing (higher/lower) relative to hatch closing at
> the start of a dive before setting off alarms?  My thought is that an alarm
> should sound well before any point of emergency.  I'm considering sounding
> a warning at 2psi +/- and an alarm at 4psi +/-  but I'm not sure if this is
> too strict.
>
> Jon
> _______________________________________________
> Personal_Submersibles mailing list
> Personal_Submersibles at psubs.org
> http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.whoweb.com/pipermail/personal_submersibles/attachments/20160224/5b72ea39/attachment.html>