| Re: Everest Climber
I didn't expect this much interest and especially that it would be this well informed. It is true the "A" team in 1953 British expedition was using a rebreather and Hillary has said they ran away from everyone. Unfortunately their system was a CaHO based system and they had cold issues on their summit attempt. It was after that the "B" team made history.
My system uses an oxygen mask MBU-5P used in in the 70's in fighters (I am also a pilot). Our objectives are not O2 conservation but high O2 partial pressures. To duplicate sea level conditions at 29,000 takes about 75% O2 concentrations. The metabolic rate remains roughly the same - about 1.35 LPM. This may seem low but keep in mind summit day on Everest is only 3,000 vertical feet and slightly less than a mile. But at that altitude the average climber, even with supplemental O2 takes about 20 minutes to go 100 meters.
Our challenges have been 1) enviromental (-20F is average on Everest summit although I climbed Vinson in Antarctica and it was colder!) 2) weight 3) ergonomics 4)simplicity. Our first challenge was to find a CO2 absorbent that was light enough and also worked at low temps. There are several but they all have challenges. The best is lithium hydroxide (LiHO) which is perfect except it is very friable and highly irritating. We found a company that had a method of encapsulating it in a gas permeable polymer matrix and roll it into corrugated sheets (at about $200 a kilo!). We have tested in a cold chamber to -30F with great success.
My primary goal now is a simple O2 monitor that we can incorporate so we can sleep on the system at higher camps. Keep in mind that in our case no one drowns if there is a system failure. You merely revert to ambient air. Alas I ramble. I'm not sure how much anyone really wants to know.
By the way your professor was right. There is no market. On the other hand there were 10 deaths including one on our expedition. Nothing could have helped in some of those cases (our climber was killed in an ice fall collapse) but a rebreather would have made it possible for some of those people to have gotten up and walked down.
Bud |