Re: Pressure regulation

["Marsee Skidmore" <heyred@email.msn.com>]

I'm planning on doing exactly what Alan Secor suggests. I should have said
that a really really really sensitive demand regulator can be used. Pressure
hull flex may influence the set point.

Alan and Dave, thanks for the scrubber info. Alan, do you plan on passive
scrubbing, or are you going to build a blower? :-o Joe
-----Original Message-----
From: SFreihof <SFreihof@aol.com>
To: personal_submersibles@psubs.org <personal_submersibles@psubs.org>
Cc: DStuelke@magick.net <DStuelke@magick.net>
Date: Friday, March 13, 1998 9:24 AM
Subject: Pressure regulation


>In your mail you asked:
>> Also to the people building dry subs, how do you regulate the fresh air
>supply >and internal pressure? I've spent many sleepless nights thinking
about
>it (it's >better than counting sheep) and have come up with a way to do it
but
>I probably >just re-invented the wheel.
>
>My understanding is that you merely replace O-2  consumed, since CO-2
produced
>is absorbed by the scrubber (lithium hydroxide, e.g.).  There is no net
>increase in pressure, and I assume you need only to keep the partial
pressure
>(i.e. percentage) of oxygen within certain limits.  Also, it is wise to
>monitor the percentage of CO-2.
>
>I'm not sure you can do this simply with a sensitive demand type regulator,
>because I would expect the hull flex at depth to increase the total
pressure
>in the cabin above 1 atm.  I would think you must monitor % 0xygen.
>
>I am sure there are ways of doing this automatically and maybe some
components
>of scuba type rebreather system could be used.  These systems are now
>commercially available, but probably expensive.
>
>I'm curious what method you devised?  Please share your design ideas,
unless
>you intend to patent, of course.
>
>Who out there can offer some guidance?
>
>Stan Freihofer
>