Use of rebreathers on high altitude climbs
Charles D. Rubin
I was wondering if anyone has considered the idea of using rebreathers
on high altitude climbs. For anyone not familiar, rebreathers are used
in SCUBA diving. They recirculate the air you breathe out, eliminate
carbon dioxide through a chemical filter, then add back a drop of oxygen
to bring the level back up to normal. Since there is 21% oxygen in
normal air, and still 18% (I think) in the air we breathe out, this
allows a single oxygen canister to last much longer.
In climbing Everest, for example, perhaps a rebreather could be worn
continuously from base camp, and the oxygen level could be maintained at
the level of base camp for the entire trek.
I am not a climber. I just read Into Thin Air, and this idea came to me.
Any feedback would be interesting...
-- Charlie
Paul Hartmann
Interesting idea! The major obstacle I see with it is weight. In SCUBA
the added weight is not an issue. At 8000m it would be. Definitely worth
pursuing.
chris maytag
Paul Hartmann wrote in message <357349...@gsosun1.gso.uri.edu>...
> <snip>
> Interesting idea! The major obstacle I see with it is weight. In SCUBA
>the added weight is not an issue. At 8000m it would be. Definitely worth
>pursuing.
Several years ago, I visited a SEAL team on a navy ship (LPD7)- "Public Relations Day" kinda thing. In addition to scary looking black guns, they had a rebreather on display. It wouldn't have been much over five kilos, if that - and was small & compact.
So, in some future lifetime in which I manage to get over 14500', I'll give it a shot.
--
] chris maytag - al...@earthling.net
] http://www.freemars.nu
] boulder, colorado, earth, sol.
] LOOK UP.
LJohnson
I do not think it would work. Something about there being more O2 in the air
around you than in your exhaled breath, Why bother stripping out CO2 when
richer air is available. The main problem is that the higher you go, the
lower the
partial O2 pressure. Traditional solution is to augment the available air
with
O2 to increase its partial pressure. Another problem is that the body does
not
work well at very high altitude, low pressure, even if there is plenty of
O2 around. A space suit would work but they are very heavy and expensive.
Frankly, I'm waiting for a personal force field to pressurize the air around
me
and an antigravity assist module to reduce my pack weight.
TIC, Lane
Charles D. Rubin wrote in message <3572FE6C...@ulster.net>...
>I was wondering if anyone has considered the idea of using rebreathers
>on high altitude climbs
>
>(snip)
GWLucky
Yes, I would imagine the main issue would be weight. After all, typical scuba
rebreathers last about as long as tanks, so the question becomes, if you are
using the rebreather for supplemental O2, do you gain anything (i.e. less
weight) per hour over conventional supplemental air? Great talking point, BTW.
The only time tank weight is an issue diving, for me, is getting in and out of
the damn boat.
hleh...@my-dejanews.com
Venting excess CO2 at altitude doesn't seem to be a problem. That leaves you
using the rebreather strictly as a means of adding some extra oxygen to your
breathing air. Seems to me that's what climbers have been doing for the last
50 years or so by carrying oxygen canisters. Now if a rebreather setup is
significantly lighter than the standard mountaineering rig, that maybe it's
worth looking at.
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Todd Clare
no kidding. I'm a climber and a diver so this is really interesting.
It seems the bottles they use for high expeditions are pretty small, and
I think that's where most of the weight of a rebreather comes from, so
it may not add excessive weight to use a rebreather designed for smaller
gas bottles? Anybody out there in search of a physiology thesis? this
would be a hell of a project to take up.
Richard Hall
Come on guys, wake up. The problem is not weight, nor is it the level
of CO2. The problem is that at elevation the air density is so thin
that getting enough oxygen is the problem. Typically they supplement
with oxygen to increase the percentage of oxygen. The air density is
still basically the same, but the percentage of oxygen to other gasses
is higher. Since a rebreather does nothing to increase the air density,
it would be no help whatsoever...
Charles D. Rubin (fal...@ulster.net) wrote:
: I was wondering if anyone has considered the idea of using rebreathers
: on high altitude climbs. For anyone not familiar, rebreathers are used
: in SCUBA diving. They recirculate the air you breathe out, eliminate
: carbon dioxide through a chemical filter, then add back a drop of oxygen
: to bring the level back up to normal. Since there is 21% oxygen in
: normal air, and still 18% (I think) in the air we breathe out, this
: allows a single oxygen canister to last much longer.
:
: In climbing Everest, for example, perhaps a rebreather could be worn
: continuously from base camp, and the oxygen level could be maintained at
: the level of base camp for the entire trek.
:
: I am not a climber. I just read Into Thin Air, and this idea came to me.
:
: Any feedback would be interesting...
:
: -- Charlie
Hal Murray
Didn't some of the (very) early Everest expeditions try
rebreathing type systems?
--
These are my opinions, not necessarily my employers.
GWLucky
In all honesty we were having a nice discussion. Until you weighed in.
Lighten up a bit next time...
Matt Goff
In article <Ety58...@news.boeing.com>, ri...@bcstectest.ca.boeing.com
says...
Rick, you are not looking at the original idea Charles posted. His idea
states clearly that that a rebreather would provide the additional O2
necessary at high altitudes without wasting the O2 lost in exhaled air.
Instead, this O2 would be captured and reused. A weight savings would be
garnered because fewer O2 tanks would be required if O2 was not "lost."
You're right, a rebreather does not increase air density. But neither
does supplemental oxygen. Both increase ppO2, though. Just think of
this concept as the same as supplemental oxygen but adding O2 capture and
reuse.
I don't think Charles is saying that you could grab a scuba rebreather
off the shelf and climb Everest. A close match would be an Electronic
Closed Rebreather sans the diluent gas (which would be easily available
from the environment). See an example of one at
<http://yi.com/home/KramerKarl/rebreather/Buddy-Inspiration/index.htm>.
I think it's a fantastic idea.
--matt.
Mike Yukish
Richard Hall wrote:
> Come on guys, wake up.
<yawn> Its not even 12:00 yet, but I guess I shall rise...
> The problem is not weight, nor is it the level
> of CO2. The problem is that at elevation the air density is so thin
> that getting enough oxygen is the problem. Typically they supplement
> with oxygen to increase the percentage of oxygen. The air density is
> still basically the same, but the percentage of oxygen to other gasses
> is higher. Since a rebreather does nothing to increase the air density,
> it would be no help whatsoever...
>
>
Normally you carry the oxygen up in a tank, and the majority of what you
deliver to the climber is expired without being used. So you get low
efficiency use ofthe oxygen you lugged up.
A rebreather could help by allowing the same oxygen bottle to last *much*
longer (couldn't it?)
From my days as a military pilot, we used to breathe 100% oxygen from
takeoff to landing, delivered at slightly over ambient pressure. Our LOX
bottles would last much longer at high altitudes, since the pressure was
lower and the quantity per breathe lower. We also used to get what I
called 'Oxygen Ear', for lack of a better name. It is where the inner ear
gets saturated with O2, and later that night when asleep your body soaks
up the O2, and you wake up having to pop your ear something fierce. But I
digress...
--
Mike Yukish
may...@psu.edu
ARL/Penn State U
http://elvis.arl.psu.edu/~may106
Elgon
Yep, the 1953 successful British one did according to John Hunt's book
about it, in addition to more conventional systems. I cannot remember,
however, whether they used them on the actual ascent or not. The idea of
the system they used AFAICR was not som much to increase th ppO2 but to
prolong cylinder life.
gaz morris
T. Fogle
Exactly! But the reason that it may work is that at 2 liters per minute you
only increase the available oxygen to about 30 percent. If you could
increase the amount of available oxygen to the lungs, increasing the
percentage of oxygen molecules available without adding too much extra
weight or using any more O's out of your cylinder, then you would be at an
advantage.
Typically high altitude climbers have oxygen saturation's (amount of
saturated hemoglobin is around 99% at normal altitudes) of less than 90. In
my line of work that's well on the way to dead for the average Joe. The only
thing is that the climbers have acclimated.
The real question should be, what is the amount of exhaled oxygen at
that altitude? What is the amount of recovered oxygen? and what is the added
weight?
Here's some facts and figures:
Respiratory rate of average person at rest: 12-16/min.
Tidal volume of average person at rest: 1.5 liters. (tidal volue is
the amount of air moved, not including whats left at the end of the breath
and not including the potential amount by taking deep breaths.)
Average amount of air moved per minute by average person at rest at
sea level 14*1.5=21 litters of air.
Bear with me now- I'm not a number cruncher:
21 liters of air divided by 21% is 4.41 litres of oxygen ordinarily
inhaled in one minute at rest.
with two litres supplemental oxygen that raises the percentage to
30% O2 or 6 litres of oxygen inhaled at rest in one minute.
To raise the percentage of oxygen inhaled to 35%, you must then increase
the oxygen available by one litre per minute. This would decrease the amount
of time you cylinder would be useful by 1/3. To recover some of the exhaled
oxygen and reuse it might increase the amount of time your cylinder is
useful by them same.
16% percent is a bit more than 3/4 of 21% right? (I didn't actually
do the math on that one). So, this average person at sea level is exhaling
3/4 of the 4.41 litres he inhales, this leaves you with at lease 3 litres to
try to recover.
By my theory there is a lot to be gained by carrying an effective
re-breather.
t-bone
Richard Hall wrote in message ...
>Come on guys, wake up. The problem is not weight, nor is it the level
>of CO2. The problem is that at elevation the air density is so thin
>that getting enough oxygen is the problem. Typically they supplement
>with oxygen to increase the percentage of oxygen. The air density is
>still basically the same, but the percentage of oxygen to other gasses
>is higher. Since a rebreather does nothing to increase the air density,
>it would be no help whatsoever...
>
>
>Charles D. Rubin (fal...@ulster.net) wrote:
>: I was wondering if anyone has considered the idea of using rebreathers
>: on high altitude climbs. For anyone not familiar, rebreathers are used
>: in SCUBA diving. They recirculate the air you breathe out, eliminate
>: carbon dioxide through a chemical filter, then add back a drop of oxygen
>: to bring the level back up to normal. Since there is 21% oxygen in
>: normal air, and still 18% (I think) in the air we breathe out, this
>: allows a single oxygen canister to last much longer.
>:
>: In climbing Everest, for example, perhaps a rebreather could be worn
>: continuously from base camp, and the oxygen level could be maintained at
>: the level of base camp for the entire trek.
>:
>: I am not a climber. I just read Into Thin Air, and this idea came to me.
>:
Todd Clare
nice! that's what I was getting at (slowly and poorly) a while ago.
It's not going to increase oxygen concentration (no rebreather does
that, not even SCUBA rebreathers -- higher concentrations of oxygen
_especially_ at higher pressures (SCUBA)are toxic -- it's called oxtox
or oxygen toxicity). All the rebreather serves to do is make the bottle
of air last longer by recycling exhaled O2. If the
rebreather-of-the-future-for-high-altitudes turns out to be light
enough, the additional energy to carry it could theoretically (thank you
T Fogle) be offset and actually overcome by the energy saved by not
carring as many O2 bottles or having to change them as often. Less
energy expended = less oxygen needed = less painful lungs on a climb.
Jim Shepherd
In article <3575AE40...@bah.com>, clare...@bah.com says...
>
> It's not going to increase oxygen concentration (no rebreather does
>that, not even SCUBA rebreathers
Actually the rebreather units do concentrate the O2. With the Draeger mine
rescue units, O2 levels approached 80-90% after the initial purge of N2.
Oxygen toxic problems occur with **increased** pressures as in scuba diving.
THere are long term problems with breathing pure O2, but these haven't been
documented at high elevations. Rebreathers do provide very moist air, and
there may be a freeze-up problem in the extreme cold as exhaled moisture
stays in the system. THere is some heating from the reaction of the CO2 with
the scrubber, but at -20 it may not be enough to prevent icing inside the
units.
Jim
swic...@hotmail.com
They are used in technical diving and also safety escape systems, The main advantages of rebreather diving are extended gas endurance, and lack of bubbles. Rebreathers are generally used for scuba applications, but are also occasionally used for bailout systems for surface supplied diving
They take loads of training and skill the systems are used in deeper dives or long times under water, they are a lot smaller and less bulky than taking normal mixed gas systems that used in deep sat diving as you need less gas the system scrubs and recycles the air breathed out as we don’t use all the oxygen that’s breathed out, the air that is inhaled is about 20-percent oxygen, and the air that is exhaled is about 15-percent oxygen, so about 5-percent of the volume of air is consumed in each breath and converted to carbon dioxide.
Therefore, a human being uses about 550 liters of pure oxygen (19 cubic feet) per day.ey
They work well but can be temperamental they have to be constantly checked and monitored if they stop working they can kill quite quickly due to breathing in carbon dioxide and lose consciousness and game over
But definitely something that takes a lot of training and skills
hlill...@gmail.com
comments. However, I will say that I have a hard time seeing the advantages of
a rebreather for high altitude mountaineering. It's more complicated than a
normal oxygen set-up and the advantages for diving don't apply. The primary
advantage for a diver is stealth. No bubbles and it's quieter. Not likely to be
an issue at 27,000 feet on K-2. It also has the advantage that the diver need
carry only oxygen since it re-uses the nitrogen, again not an issue at altitude.
For a good summary of advantages for divers, see
https://oceanicventures.com/rebreather-scuba-diving-the-advantages-of-silent-scuba-diving/
One thing that I suspect might be useful at altitude is something I've seen
advertised for medical uses. It concentrates oxygen from the air, freeing the
patient from the weight of tanks and need to change tanks so frequently. Would
that work at 27,000 feet? I don't know but suspect it would. Batteries might
be an issue, however.
hlill...@gmail.com
this.
lee.thomp...@gmail.com
lee.thomp...@gmail.com
It makes deadly dives possible and rescues the risk of decompression I’llness and reduces weight as you don’t need 5 tanks of different mix hanging off you to do the same dive profile, each swap is a risk.
hlill...@gmail.com
> The primary benefit is nothing to do with silence and bubbles unless you are a photographer, it’s all to do with the correct Po2 at all times, you do less deco at depth:
> It makes deadly dives possible and rescues the risk of decompression I’llness and reduces weight as you don’t need 5 tanks of different mix hanging off you to do the same dive profile, each swap is a risk.
There is air at altitude, just not as much as nearer sea level. And climbers seldom
face pressure that changes as fast as do divers. The issue at altitude is getting
enough oxygen. Something that concentrates the oxygen as some medical devices do
seems more useful.
jem...@gmail.com
hlill...@gmail.com
> The aDvantage is.. You don't run out on the way down.. When most people die cause their either tired or their empty O2 has left them incapable of finishing the decent to below the death zone etc...
on how much O2 they can provide. The obvious question is battery life and function
in the cold at high altitudes. I've not found anything about their use for
mountaineering but there is a discussion about them for medical use at
https://www.usoxygensales.com/resources/news-articles/oxygen-concentrators-high-altitudes/
And a link to many such concentrators at
https://www.usoxygensales.com/all-portable-oxygen-concentrators/
wacki zacki
> > Come on guys, wake up.
> > of CO2. The problem is that at elevation the air density is so thin
> > that getting enough oxygen is the problem. Typically they supplement
> > with oxygen to increase the percentage of oxygen. The air density is
> > still basically the same, but the percentage of oxygen to other gasses
> > is higher. Since a rebreather does nothing to increase the air density,
> > it would be no help whatsoever...
> >
> >