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I concur with Phil's observation on looking for a CO2
absorbent material that will perform at low temperatures. While working at
Diving Unlimited International (DUI), I was involved in the production of bell
diving and saturation chamber rescue kits. There were two parts to these units:
a lung-powered rebreather bag that you could reload with absorbent over the 72-hr.
window for rescue and a highly compressed, high-loft sleeping bag to maintain
warmth. It is better not to depend on power for operating your emergency life
support equipment in case you have a complete loss of power (partial flooding
with ensnarement that does not allow for an egress and free ascent). Any
energy captured within the hull will be quickly drawn out through conduction
through the hull so additional thermal protection should also be considered.
Remember, 1-1/2 hr. exposure to 72° F. water will leave you mildly hypothermic...you'll have a
longer time in a dry hull but it will still get you. Lithium hydroxide (LiOH)
may look like a great absorbent material (~8 times as effective as more common
absorbent materials and it gives off heat to help keep you warm) but it reacts
nastily with water. Another thought is moisture/humidity control within the
hull. Your body sweats about 1 to 1-1/2 cups of water an hour and your breath
will give off probably 2 cups. High humidity and electronics don't mix very
well. This humidity also will quicken your chilling and make things messy in
an emergency over time. Respectfully, Jay K. Jeffries |