Rebreather to the TOP!

frankis

Hey!

We are some students from Trondheim Norway, and were working on a quite interesting project.
In high altitude climbing, such as Everest, the need of oxygen is obvious.
Why not use a closed circuit system? We off cource have to develop the solutions used in diving, but we think we can produce a better system than the one used today (that is conventional open circuit system, with compressed air)


Any comments or suggestions?

jhaaja

I guess the climbers use open circuit oxygen

CC might work, but you will get more weight on the system from the scrubber and the lung/s. But you also should be able to come by with a smaller HP cylinder of O2.

Interesting project!
Maybe a basic LAR-5 type of O2 Rebreather would be quite easily adapted to that use...

JH
Finland

Chris

Why bother, the amount of people that climb Everest and other peaks high enough to maybe need O2 is it worth the investment?

I trekked to Everest base camp 10 years ago, in a 2 month walking and climbing expedition around the Himalayas with Tashi Tenzing, Tenzing Norgay's grandchild (One of the best trips of my life). Anyway The amount of spent O2 bottles and rubbish at base camp was just staggering, even after some major clean-ups. I reckon the last thing you need is piles of spent indicating sorb all over the mountain as well.

Cheers
Chris

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jaap

Yes that sound like something that could be useful.

Found this:
http://www.velocitypress.com/pages/closedcircuit.php

Google on say: high altitude climbing rebreather

And you will find some more.

My guess is that a short hose pendelum Rebreather with a carbonfiber O2-tank having a metal inner layer to prevent the O2 escaping over time could be efficent weight wise. But you would have to carry a lot of sorb...

Or using potassium superoxide (KO2) as both the scrubber and O2 source. That stuff gives you approx 3/2 O2-molceules per CO2 that is scrubbed.
So it will save a lot of weight compared to bringing gaseous O2 along.

KO2 is used in aircraft to generate O2 for passengers in emergencys so its a proven O2 source and has a better O2/weight ration than using tanks.
Downside is that is reacts rather violently with water, but since your not going to dive with it it should work.

Duncan Price

Closed circuit units were used on the first ascent by Hunt's party in 1952. I don't have Hillary's book "High Adventure" to hand but I understand that the party before Hillary and Tensing almost got to the summit on closed circuit O2 - I think they turned back due to problems with the rebreathers. Then Hillary and Tensing went to the top on open circuit O2.

Superoxide sounds a good idea.

I was involved in a project to develop a CCR for mines and cave resuce use in foul air environment. Never really got off the drawing board though we all hoped that we'd get cheap/free units which we could then convert for diving.

Mdemon

The main comment would be about protecting the sofnalime from freezing. Maybe the other absorbents are more resilient? You'd need to store the slime in bags inside your clothes.

The flip side is that you could have a thin scrubber tucked inside your inner gear, keeping the scrubber protected, you warm and you get the benefits of warmed air. At "minus lots", that would be quite comfortable...

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lizardland

Get off my project!!!

I'd suggested this a couple of years ago as a subject for my diving science Masters research project and my tutor whinged about it and wouldn't agree to it. Good luck with it, guess that shows I have some good ideas afterall!!!

Anway... I thought there may be other advantages as well that would offset to a certain extent altitude sickness. Mountain air is extremely dry and dehydration is a massive contributor to altitude sickness, obviously rebreathers produce a very moist gas. I was interested in how this may affect climbers' performance. Similarly, I also wondered about how breathing hot gas would affect them. Another question, we all know scrubbers become less efficient at depth when gas becomes dense so does that mean they become more efficient at altitude where pressure is very low?

I don't think there would be a weight increase. As only about 1/4 of the O2 volume would be required there is a much smaller bottle so really it is scrubber size that becomes crucial. Surely the weight saved by the bottle would be enough for a scrubber?

I think for a similar duration that OC and CC systems would probably be about the same weight. I guess the question would come down to is how physiologically different is breathing CC oxygen? Is it more advantageous? Unless the answer was yes then I doubt whether CC oxygen is an option. And can this be balanced with the risk assessment? A rebreather has more parts so more chance of failure.

Best of luck,

Stuart

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johnv

The problem is the scrubber and the compexity of th unit, both in terms of weight and operating temperature - divers worry about "cold" water, which is tepid by comparison to the external temperature experienced by high altitude mountaineers.

you have only to see how light a composite cylinder is compared to scrubber for 8 - 10 hours that must work at -30c

John

Sutty

There's a group from UCL planning an Everest trip with rebreathers in 2007.

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E-man

As others have stated, there is already a project working on this...Lithium isnt as sensitive to the cold as calcium is as ya dont need water in the absorbent. I like what somebody said about KO2 that would definatly be interesting.

You could carry a 1/4 of the oxygen....sounds much better than hauling tons of huge tanks of O2.