Removing
the CO2 from the cockpit: When we breathe from a dive reg, we're breathing
with no (surrounding) feedback because there's no "cockpit". It's
the trigger from the increasing CO2 in our blood and lungs and, to some
degree, a drop in O2, as well, that gets us breathing. No cabin
atmosphere required. A really experienced diver can up the CO2
ante in his or her lungs by developing a tolerance for the CO2 - skip
breathing. Never was my favourite
pastime.
As
far as O2 and barometric pressure, I'd use a constant flow of O2 - I think ~
1/2 a litre/min. was the magic number. I don't know how I'd monitor the
cabin, however. It could very well be that ambients and current air
sampling methods are incompatible. More research on my part. I'll
let the group know what I find. However, our friend Dalton may disagree
with me regarding partial pressures at depth.
One
alternative is to forego O2 altogether and just bleed air into the
cabin. The PP of oxygen should be solved, but, I'd still like to
have an O2 sensor.
My
plan is to remove as much moisture as I can - it kills vis on the
dome and is a general pain in general for just about everything from
clothing to electronics to corrosion. I'm thinking CPU fans (like a CO2
scrubber) and desiccant, of which I have loads. I don't have any
numbers yet or even if it'll work well at depth.
As
far as 4x the moisture, keep in mind that scuba tanks provide bone-dry
air. What I'd be really curious about is whether, because of
Dalton, 4x the humidity would be drawn out of our lungs as we
breathe out. You bring up a good point. And dehydration may
come in the back door as a side issue. I'd never thought about
that.
-----
Original Message -----
Sent:
Thursday, October 22, 2009 12:06 PM
Subject:
Re: [PSUBS-MAILIST] DeepWorker's scrubbers
I
havn't quite got my head around what happens
with
the
life support in an ambient, but will comment in case
If
you scrub out the CO2 in an ambient you take
away
a
physiological tool that tells your brain theres too
much
CO2
& hence not enough O2. With lack of O2 you
pass
out
with no warning. You also don't have the added
safety
feature
of a barometer monitering pressure to indicate
a
drop in O2 levels. You can't use the bellows add
method
of Phil Nuytten wich relies on changes of cabin
pressure
to add O2 in an ambient.
Jay
commented that O2 monitors don't work well in
high
moisture
environments wich you get in ambients. ( ie at
100ft
you have 4x the moisture as you have 4x the
air.)
Then
you have to do calculations for your depth re the
PPO2
(partial pressure of O2). You may have enough O2
at
depth, but as you approach the surface the O2%
can
change
dramatically & you can suffer a shallow water black
You'd probably
need to read up on rebreathers & diving with
them
to perfect the system.
It
also depends on how big your cabin is. You might
find
that
if you have a certain flow of O2 in you'll never run
out
for
your expected dive duration.
Apparently
you're at a greater fire risk with higher levels
of
O2 in the cabin. So watch that you're wiring
insulation
is
not of a material that will combust easily.
There
is a discription of how to build a scrubber on the
-----
Original Message -----
Sent:
Thursday, October 22, 2009 9:42 PM
Subject:
Re: [PSUBS-MAILIST] DeepWorker's scrubbers
For
years I'd been avoiding the whole idea of scrubbers: too noisy,
maintenance, etc.
After
my experience with DeepWorker I do believe I've become a convert.
Those fans were so quiet. And no spider mask on my head or
oral/nasal mask glommed onto my face. I could breathe and talk
normally. Sigh. There was even a nice breeze. It takes
some of us a while.
[a]
Is the DW scrubber design open to discussion - is it so simple you can
share what makes it work for DW? I'd love to have a design handed to
me or be steered in that direction. I did find something on the Net
but it requires machining. Built originally for a
rebreather.
[b]
Next: would the scrubbers be any trouble in a
dry-ambient?
[c]
How's breathing moisture handled in DW?