Oxygen above 20,000 feet

I seem to recall that my portable 02 system said something about not
being about to go above 20,000 feet with it. This does not present a
problem with my Turbo Arrow since that represents its service ceiling.
Now, I am contemplating a Cessna Turbo 310 R and I am wondering whether
the 02 will be the limiting factor on how high I fly?

-Sami

Yes, I think so. So if I use a mask, then is there some upper limit?
This seems counter-intuitive. It seems like nasal canulas deliver
oxygen more directly into the lungs (assuming you are a nose
breather)...especially if you use a pusher (a little device that detects
when you breath and pushes O2 to you...and then shuts it off when you
are not breathing). What am I misunderstanding here?

-Sami


Aaron Coolidge wrote:

O. Sami Saydjari wrote:
: I seem to recall that my portable 02 system said something about not
: being about to go above 20,000 feet with it. This does not present a
: problem with my Turbo Arrow since that represents its service ceiling.
: Now, I am contemplating a Cessna Turbo 310 R and I am wondering whether
: the 02 will be the limiting factor on how high I fly?

: -Sami

For some reason, the nasal "cannula" oxygen systems state they should not
be used over 18000 feet. Perhaps this is the limit you're thinking of?

"O. Sami Saydjari" wrote in message
...
Yes, I think so. So if I use a mask, then is there some upper limit?
This seems counter-intuitive. It seems like nasal canulas deliver
oxygen more directly into the lungs (assuming you are a nose
breather)...especially if you use a pusher (a little device that detects
when you breath and pushes O2 to you...and then shuts it off when you
are not breathing). What am I misunderstanding here?

-Sami


A mask is more of a sealed system, whereas a canula allows a leak out of
your nose. With the air that thin, I would think the oxygen coming out would
migrate towards the atmosphere a lot faster than into you.
Another thing to ponder might be the physical strength of the O2 bottle, it
may not be safe at the reduced atmospheric pressure at higher altitudes.

most "standard" masks are not sealed.. but have rebeather bags.. and are not
suited about 25,000ft

above 25,000 unpressurized you should have a military aviators style mask
with pressure regulator

BT

"Mike W." wrote in message
...

"O. Sami Saydjari" wrote in message
...
Yes, I think so. So if I use a mask, then is there some upper limit?
This seems counter-intuitive. It seems like nasal canulas deliver
oxygen more directly into the lungs (assuming you are a nose
breather)...especially if you use a pusher (a little device that detects
when you breath and pushes O2 to you...and then shuts it off when you
are not breathing). What am I misunderstanding here?

-Sami


A mask is more of a sealed system, whereas a canula allows a leak out of
your nose. With the air that thin, I would think the oxygen coming out
would
migrate towards the atmosphere a lot faster than into you.
Another thing to ponder might be the physical strength of the O2 bottle,
it
may not be safe at the reduced atmospheric pressure at higher altitudes.

I think the other posters have it right. The specific concept behind
it, if I remember my science fiction books correctly, is 'partial
pressure'. With the open cycle (the one that hooks to your nose),
there's an open path direct to the low pressure area through your
mouth. The oxygen enters your lungs through osmosis, and if the
pressure on the inside of the hemoglobin in your pulmonary capillary is
greater then the pressure of the O2 against it, it just won't enter.

Another part of the problem may be that at high enough altitudes, CO2
may no longer be effective at triggering the breathing impulse.

I think the partial pressure issue is probably more relevant.

If someone here is a doctor or actually KNOWS the answer, feel free to
tell me where I pooched it up. My education comes from the likes of
Del Rey Publishing and Baen Books, not John Hopkins.

Ben Hallert
PP-ASEL

The oxygen tank will be safe at altitude. Normally they contain a pressure
of 1200 to 2000 PSI, while sea level atmospheric pressure is 14.7 PSI. Even
in a vacuum the pressure differential between the atmosphere and inside the
tank is miniscule.

Very good answer Ben!
The partial pressure of O2 at FL180 is 50% that of sea level.
As you go higher, the rate of partial pressure change decreases more
rapidly, so that by FL270 it is into single digits.
A pressurized mask is necessary to force the air into your lungs and
into your blood.

Ben Hallert wrote:
I think the other posters have it right. The specific concept behind
it, if I remember my science fiction books correctly, is 'partial
pressure'. With the open cycle (the one that hooks to your nose),
there's an open path direct to the low pressure area through your
mouth. The oxygen enters your lungs through osmosis, and if the
pressure on the inside of the hemoglobin in your pulmonary capillary is
greater then the pressure of the O2 against it, it just won't enter.
Another part of the problem may be that at high enough altitudes, CO2
may no longer be effective at triggering the breathing impulse.
I think the partial pressure issue is probably more relevant.

"Mike W." wrote in message
...

Another thing to ponder might be the physical strength of the O2 bottle,
it
may not be safe at the reduced atmospheric pressure at higher altitudes.

That's a myth, the bottles will certainly not have a problem handling the
minimal changes in pressure at altitude.

Juan

Another thing to ponder might be the physical strength of the O2 bottle,
it
may not be safe at the reduced atmospheric pressure at higher altitudes.

They why carry it? O2 tanks are pressure tested every 5 years.. a standard
O2 tank should be able to go to 50,000ft.. but you'll need a pressure
regulator and fitted sealed mask for pressure breathing

BT

OK, very helpful answers. But, how does one get a "pressurized mask"?
Is this a matter of buying a pressurized mask and hooking it to a
built-in O2 system (such as might be found on a Cessna Turbo 310), or is
there something special about the 02 system itself that is needed. It
sounds like one needs a special pressure regulator like one might find
in Scuba equipment. I ask this because I want to know what to ask for
when I am looking at Turbo Cessna 310s in terms of an adequate O2 system
to make it up to its 28,000 ft service ceiling.

-Sami


john smith wrote:

Very good answer Ben!
The partial pressure of O2 at FL180 is 50% that of sea level.
As you go higher, the rate of partial pressure change decreases more
rapidly, so that by FL270 it is into single digits.
A pressurized mask is necessary to force the air into your lungs and
into your blood.

Ben Hallert wrote:

I think the other posters have it right. The specific concept behind
it, if I remember my science fiction books correctly, is 'partial
pressure'. With the open cycle (the one that hooks to your nose),
there's an open path direct to the low pressure area through your
mouth. The oxygen enters your lungs through osmosis, and if the
pressure on the inside of the hemoglobin in your pulmonary capillary is
greater then the pressure of the O2 against it, it just won't enter.
Another part of the problem may be that at high enough altitudes, CO2
may no longer be effective at triggering the breathing impulse.
I think the partial pressure issue is probably more relevant.