O2 Concentrator instead of O2 tank

"Bill Denton" wrote in message
. ..
But we aren't discussing the concentration of O2...

Uh...have you looked at the subject of this thread?

In any case, the question of using supplemental oxygen cannot be discussed
*without* bringing concentration of O2 into it. Supplemental oxygen as used
in non-pressurized, general aviation airplanes always works by increasing
the concentration of oxygen.

What we are providing is a constant stream of pure O2. It may come from a
tank, or it may come from a concentrator.

How can you say that "it may come from a concentrator" and still claim we
are not discussing the concentration of O2?

Think of a Mason jar...

At sea level, we take an open jar and put the lid on it. The jar now
contains "X" amount of air, of which 21% is oxygen.

True.

We take another open jar to 20,000 feet and put the lid on it. The
concentration of oxygen remains at 21%, but because the air is thinner,
the
amount of air in the jar is LESS than the "X" amount in the "sea level"
jar.

True.

If we extract the nitrogen from both jars, the "sea level" jar will
contain
more oxygen than the "20,000 feet" jar.

True.

You would not net any additional oxygen from the concentrator...

"Additional" as compared to what? It's true that a concentrator doesn't add
new oxygen to the ambient atmosphere aloft. But it most certainly does "net
any additional oxygen" for the person breathing air supplemented by the
output of the concentrator. That's the whole point. By combining the
output of the concentrator with ambient air inhaled by the pilot (or other
person), the concentration of O2 in the inhaled air is higher than the
ambient 21%. This is exactly how supplemental O2 from a tank works as well.

Pete

Bill Denton writes:

Think of a Mason jar...

At sea level, we take an open jar and put the lid on it. The jar now
contains "X" amount of air, of which 21% is oxygen.

We take another open jar to 20,000 feet and put the lid on it. The
concentration of oxygen remains at 21%, but because the air is thinner, the
amount of air in the jar is LESS than the "X" amount in the "sea level" jar.

If we extract the nitrogen from both jars, the "sea level" jar will contain
more oxygen than the "20,000 feet" jar.

You would not net any additional oxygen from the concentrator...

You would get air that has a higher percentage of oxygen, so the
absolute amount of oxygen in this enriched air at 20,000 feet might
well be equal to or greater than the amount in normal unenriched air
at sea level.

This is already done for astronauts. They breathe a low-density
atmosphere (like being at high altitude), but it has a much higher
percentage of oxygen than normal air. It allows engineers to use less
pressurization, which saves weight and wear and tear.

Divers do the opposite: as they increase the air pressure at depth,
they reduce the percentage of oxygen in the air so that they aren't
poisoned by it (it is toxic in the high amounts that can be taken in
at high pressures).

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On Sat, 02 Dec 2006 21:27:30 +0100, Mxsmanic
wrote in :

if oxygen concentrators are (or will become) sufficiently
efficient and economical, they could offer an alternative to cabin
pressurization, on both GA and commercial aircraft.

Up to a point:

http://www.mountainhighoxygen.com/in...6&article_id=3
At a pressure altitude of 34,000 ft. the lungs are compromised so
much in the ability to transfer gases to the blood and air that
the oxygen saturation level will drop to only 30%. Total
unconsciousness will result in 3 to 4 minutes. At this point a
person breathing 100% oxygen would not benefit from the supply
because pressures in water vapor and tissues will be the same as
the absolute pressure of oxygen (0.76 psia) where nearly nothing
is transferred. One would need to be using a full
pressure-demand-type oxygen mask.

Someone was sleeping during Physics class...

Jim



"Bill Denton" wrote in message
. ..
But we aren't discussing the concentration of O2...

What we are providing is a constant stream of pure O2. It may come from a
tank, or it may come from a concentrator.

Think of a Mason jar...

At sea level, we take an open jar and put the lid on it. The jar now
contains "X" amount of air, of which 21% is oxygen.

We take another open jar to 20,000 feet and put the lid on it. The
concentration of oxygen remains at 21%, but because the air is thinner,
the
amount of air in the jar is LESS than the "X" amount in the "sea level"
jar.

If we extract the nitrogen from both jars, the "sea level" jar will
contain
more oxygen than the "20,000 feet" jar.

You would not net any additional oxygen from the concentrator...

Larry Dighera writes:

Up to a point:

http://www.mountainhighoxygen.com/in...6&article_id=3
At a pressure altitude of 34,000 ft. the lungs are compromised so
much in the ability to transfer gases to the blood and air that
the oxygen saturation level will drop to only 30%. Total
unconsciousness will result in 3 to 4 minutes. At this point a
person breathing 100% oxygen would not benefit from the supply
because pressures in water vapor and tissues will be the same as
the absolute pressure of oxygen (0.76 psia) where nearly nothing
is transferred. One would need to be using a full
pressure-demand-type oxygen mask.

True, but how many prop-driven general aviation aircraft have a
service ceiling of 34,000 feet or above?

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On Sun, 03 Dec 2006 02:28:35 +0100, Mxsmanic
wrote in :

Larry Dighera writes:

Up to a point:

http://www.mountainhighoxygen.com/in...6&article_id=3
At a pressure altitude of 34,000 ft. the lungs are compromised so
much in the ability to transfer gases to the blood and air that
the oxygen saturation level will drop to only 30%. Total
unconsciousness will result in 3 to 4 minutes. At this point a
person breathing 100% oxygen would not benefit from the supply
because pressures in water vapor and tissues will be the same as
the absolute pressure of oxygen (0.76 psia) where nearly nothing
is transferred. One would need to be using a full
pressure-demand-type oxygen mask.

True, but how many prop-driven general aviation aircraft have a
service ceiling of 34,000 feet or above?

I have no idea, but that's another subject. And you were referring to
commercial aircraft as well as GA:

if oxygen concentrators are (or will become) sufficiently
efficient and economical, they could offer an alternative to cabin
pressurization, on both GA and commercial aircraft.


There are other issues also. There are the FARs:

§ 91.211 Supplemental oxygen.

(a) General. No person may operate a civil aircraft of U.S.
registry—

(1) At cabin pressure altitudes above 12,500 feet (MSL) up to and
including 14,000 feet (MSL) unless the required minimum flight
crew is provided with and uses supplemental oxygen for that part
of the flight at those altitudes that is of more than 30 minutes
duration;

(2) At cabin pressure altitudes above 14,000 feet (MSL) unless the
required minimum flight crew is provided with and uses
supplemental oxygen during the entire flight time at those
altitudes; and

(3) At cabin pressure altitudes above 15,000 feet (MSL) unless
each occupant of the aircraft is provided with supplemental
oxygen.

(b) Pressurized cabin aircraft. (1) No person may operate a civil
aircraft of U.S. registry with a pressurized cabin—

(i) At flight altitudes above flight level 250 unless at least a
10-minute supply of supplemental oxygen, in addition to any oxygen
required to satisfy paragraph (a) of this section, is available
for each occupant of the aircraft for use in the event that a
descent is necessitated by loss of cabin pressurization; and

(ii) At flight altitudes above flight level 350 unless one pilot
at the controls of the airplane is wearing and using an oxygen
mask that is secured and sealed and that either supplies oxygen at
all times or automatically supplies oxygen whenever the cabin
pressure altitude of the airplane exceeds 14,000 feet (MSL),
except that the one pilot need not wear and use an oxygen mask
while at or below flight level 410 if there are two pilots at the
controls and each pilot has a quick-donning type of oxygen mask
that can be placed on the face with one hand from the ready
position within 5 seconds, supplying oxygen and properly secured
and sealed.

(2) Notwithstanding paragraph (b)(1)(ii) of this section, if for
any reason at any time it is necessary for one pilot to leave the
controls of the aircraft when operating at flight altitudes above
flight level 350, the remaining pilot at the controls shall put on
and use an oxygen mask until the other pilot has returned to that
crewmember's station.

And if I recall correctly, above 25,000' a pressure mask or cabin
pressurization are required due to human physiology. Read what is at
the link I posted in my followup article, and you'll get a clue.
Here's another quote:

At 20,000 ft. the absolute pressure altitude drops to 6.75 psia.
and the oxygen pressure drops to 1.38 psia. This is less than half
that at sea level. Oxygen saturation of the blood drops to 62 to
64% at this pressure altitude. Unconscious collapse and/or
convulsions will result within 10 to 15 minutes of exposure. Death
is not uncommon as a result of complications acquired from long or
quickly changing exposures to low partial pressures (high
altitudes) without supplemental oxygen or pressurized cabins.

Bill Denton wrote:

At altitude, the air still contains 21% oxygen. But since the air is
"thinner", it contains less oxygen than does the air at sea level.

So removing the nitrogen doesn't actually provide any additional oxygen at
altitude.

The "amount" of oxygen is of little importance. The thing that controls
perfusion is the partial pressure of O2.

If we extract the nitrogen from both jars, the "sea level" jar will contain
more oxygen than the "20,000 feet" jar.

You would not net any additional oxygen from the concentrator...

Instead of a (glass) jar, use a (plastic) bottle. When you take out the
nitrogen, the air pressure around the bottle will crush the bottle.
Yes, there is less oxygen in the (now smaller) bottle, but the oxygen
concentration is much higher. If you took out all the nitrogen, you'd
have almost pure oxygen.

This (partially) crushed bottle will have more oxygen per cubic inch,
even at altitude, than the sea level bottle at sea level.

Jose
--
"There are 3 secrets to the perfect landing. Unfortunately, nobody knows
what they are." - (mike).
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Yes, there is less oxygen in the (now smaller) bottle,

(by which I mean less oxygen than in the sea level bottle. There is the
same amount of oxygen in the high altitude bottle as there was before,
which was (of course) less than what was in the sea level bottle.)

Jose
--
"There are 3 secrets to the perfect landing. Unfortunately, nobody knows
what they are." - (mike).
for Email, make the obvious change in the address.

Jim Macklin wrote:
If you don't increase the concentration of oxygen, but are
merely removing N, the partial pressure of the oxygen will
not increase.

Sure it would, Jim. It works at sea level and it works at 20,000 feet.
The concentrator has no way of knowing its at altitude in a plane and
"isnt supposed to work".

If you remove all the nitrogen from a room air source, but maintain the
same atmospheric pressure, you HAVE increased the partial pressure of
oxygen. You may not have increased the total pressure, but surely you
have increased the partial pressure of the oxygen fraction of the
inspired gas.

Dave