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Alan, you might also consider the location of the exhaust (extension) from
the scrubber as well as the intake so that you don't get short recirculation
from the two being too close together. My thought is that the further
apart you can have them consistent with practicality and the design
requirements of other component of the craft, the better circulation
you will have in the sub for all purposes. However I'm certainly open to
correction.
In your design does the pilot remain approximately in the same
position or move to different locations within the sub?
Jim T
In a message dated 6/13/2010 11:42:08 P.M. Central Daylight Time,
irox@ix.netcom.com writes:
Hi
Alan,
checkout page 419 of Manned Submersibles by Frank Busy.
This gives
some formulas which can be used to calculate the CO2 build up
taking
into account the volume of the pressure hull (well, the
floodable
volume per person). You should be able to find this book a
several
sources online (including psubs I think), this is a great
reference
particularly aimed towards small
submersibles.
Cheers,
Ian.
-----Original
Message-----
From: Alan James
Sent: Jun 13, 2010 10:52
PM
To: personal_submersibles@psubs.org
Subject: [PSUBS-MAILIST]
scrubbers
To All,
While looking
at various papers on CO2 scrubbers
from manufacturers
etc, I found that
none addressed the unique
situation found in submarines.
Most CO2
absorbent is used in anesthetic machines
or rebreathers where
there is
a closed circuit. The CO2 breathed out
goes straight into the scrubber
& is removed.
In our subs the CO2 is breathed out & is
diluted by the rest of the air in the
hull & only air with a
portion of the CO2 in
the hull goes through the scrubber.
This means
that the CO2 level & the pressure in
the hull will progressively
climb
unless the volume of air going through the scrubber
is large
enough to make an
impact. The Deep Worker 2000 has fans pushing 160
liters per minute, I'm not
sure whether this is per scrubber &
whether
they have 2 scrubbers working
simultaneously. But based on 1
fan going, that's
320 x the volume of CO2 being
produced. In the
manufacturers guidelines for
scrubbers they recommend that the flow
is
at least equal to
the tidal volume of your breath (about 10 liters per
minute)
& low enough so that the air has at least 1/2 a second dwell
time in the canister.
This could be 32 x less than what Phil has worked
out is necessary for the
Deep Worker. I know
the Deep Worker has a
small hull & that fluctuations in O2
& CO2 are more critical than
a K250, but possibly the same volume of flow is
necessary to achieve
atmospheric control in larger subs.
Also because of the dwell time
needed the large
flow required would need large or
long canisters. Deep
Worker has 2x 3.35 kg
scrubbers.
On the psub site there is reference to
rebreather
cartridges as an option, but from
what I've found you would
probably need a number of
these running simultaneously
to make head
way.
What are ABS recommendations? & what are others
thoughts /
experiences with this.
I'm trying to sort this stuff out for
myself.
Regards
Alan
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