Does anyone use an oxygen concentrator to supply pilot and passengers
in a light plane flying over 14000 feet? A quick google did not turn
up anything but home units and a recent ruling that they can be used on
commercial airlines, but I did not find anything about their use on
private planes.

They don't require more than about 100 watts, so an aircraft electrical
system could keep them going as long as the engine was running.
Internal batteries would keep it alive in an emergency.

Seems like a nice solution to elimination of messing with refilling
tanks.

tom

Recently, tom > posted:

> Does anyone use an oxygen concentrator to supply pilot and passengers
> in a light plane flying over 14000 feet? A quick google did not turn
> up anything but home units and a recent ruling that they can be used
> on commercial airlines, but I did not find anything about their use on
> private planes.
>
> They don't require more than about 100 watts, so an aircraft
> electrical system could keep them going as long as the engine was
> running. Internal batteries would keep it alive in an emergency.
>
I can see a couple of possible difficulties with this related to the
required power. I presume that the home units are intended to supply a
single person? If so, a 4-pax installation would require 4x the power. At
12v, 100w = 8.3 amps; 400w = 33.2 amps (half those for 24v systems).
That's a lot of juice to draw.

Neil

On Sat, 02 Dec 2006 11:42:08 GMT, "Neil Gould"
> wrote in
>:

>At 12v, 100w = 8.3 amps; 400w = 33.2 amps (half those for 24v systems).
>That's a lot of juice to draw.

I thought about that too, but IIRC cigar lighters are fused at 10A,
and the pilot alone can operate on oxygen up to 15,000' for thirty
minutes without oxygen for passengers:



§ 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
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.
...

O2 Concentrators work by removing nitrogen from the ambient air, leaving the
oxygen, which comprises 21% of the air.

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.

So, would a concentrator even provide any benefits?



"Larry Dighera" > wrote in message
...
> On Sat, 02 Dec 2006 11:42:08 GMT, "Neil Gould"
> > wrote in
> >:
>
> >At 12v, 100w = 8.3 amps; 400w = 33.2 amps (half those for 24v systems).
> >That's a lot of juice to draw.
>
> I thought about that too, but IIRC cigar lighters are fused at 10A,
> and the pilot alone can operate on oxygen up to 15,000' for thirty
> minutes without oxygen for passengers:
>
>
>
> § 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
> 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.
> ...

"Bill Denton" > wrote in message
t...
> O2 Concentrators work by removing nitrogen from the ambient air, leaving the
> oxygen, which comprises 21% of the air.
>
> 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.
>
> So, would a concentrator even provide any benefits?

Yes, because you are breathing air with a higher concentration of oxygen,
wich will result in higher blood oxygen saturation levels. My wife has used
one of those battery operated concentrators for commercial air travel with great
results. They are a fairly new product, and cost around 5 AMUs.

To solve the power problem, it would be theoretically possible to build a
concentrator with a belt-driven compressor as a permanent installation in a
aircraft. It would not be cheap, but it would be far cheaper than
pressurization. Perhaps some clever engineer could build a dual vacuum
pump/compressor to bolt on the same engine pad as your vacuum pump. With an
installation like that, you could afford to fly with oxygen always and enjoy the
better eyesight and quicker thinking that comes with 100% blood oxygen
saturation.

Vaughn

> Does anyone use an oxygen concentrator to supply pilot and passengers
> in a light plane flying over 14000 feet? A quick google did not turn
> up anything but home units and a recent ruling that they can be used on
> commercial airlines, but I did not find anything about their use on
> private planes.
>
> They don't require more than about 100 watts, so an aircraft electrical
> system could keep them going as long as the engine was running.
> Internal batteries would keep it alive in an emergency.
>
> Seems like a nice solution to elimination of messing with refilling
> tanks.
>
> tom
>
This is done in military helicopters--oxygen for the crew and dry nitrogen
for the air space in the fuel tanks. By now, it is almost certainly done in
some other aircraft as well.

I have believed for some that this would be a good primary method to supply
oxigen in light civil aircraft--with "candles" such as the airlines use as
emergency backup.

Try a Google or WebCrawler search with the argument: oxygen + concentrator
(or) oxygen + concentrator + aircraft

Peter

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

Pure O2 in a tank, delivered to a mask to displace some of
the ambient air and replace the displaced portion certainly
raises the O2 partial pressure. But an O2 concentrator
doesn't seem to have a pressure function or am I missing
something?



"Vaughn Simon" > wrote in
message
...
|
| "Bill Denton" > wrote in message
| t...
| > O2 Concentrators work by removing nitrogen from the
ambient air, leaving the
| > oxygen, which comprises 21% of the air.
| >
| > 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.
| >
| > So, would a concentrator even provide any benefits?
|
| Yes, because you are breathing air with a higher
concentration of oxygen,
| wich will result in higher blood oxygen saturation levels.
My wife has used
| one of those battery operated concentrators for commercial
air travel with great
| results. They are a fairly new product, and cost around
5 AMUs.
|
| To solve the power problem, it would be theoretically
possible to build a
| concentrator with a belt-driven compressor as a permanent
installation in a
| aircraft. It would not be cheap, but it would be far
cheaper than
| pressurization. Perhaps some clever engineer could build
a dual vacuum
| pump/compressor to bolt on the same engine pad as your
vacuum pump. With an
| installation like that, you could afford to fly with
oxygen always and enjoy the
| better eyesight and quicker thinking that comes with 100%
blood oxygen
| saturation.
|
| Vaughn
|
|

Larry Dighera > wrote:

> I thought about that too, but IIRC cigar lighters are fused at 10A,
> and the pilot alone can operate on oxygen up to 15,000' for thirty
> minutes without oxygen for passengers:

I flew at 14,000 once with O2 for myself and co-pilot only and the boy in
the back seat vomited into a bag about halfway into the trip.

At that point I realized it was wrong of me to assume that just because the
FARS allow it that it must be safe. Never again.

--
Peter

"Jim Macklin" > writes:

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

If you remove N, the concentration of everything else necessarily
increases, at constant pressure.

--
Transpose mxsmanic and gmail to reach me by e-mail.

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

Sure it does. With (some of) the nitrogen gone, the air is thinner, and
lower pressure. The surrounding air squeezes it all together, including
the oxygen, which is now more concentrated. Ultimately, volume does not
remain constant, but pressure does.
--
"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 in message
...
> If you don't increase the concentration of oxygen, but are
> merely removing N, the partial pressure of the oxygen will
> not increase.

Ummm, yes it does. You ARE incresing the concentration of oxygen by
removing the nitrogen and using what is left. Partial pressure is based on the
concentration of a given gas and a higher concentration of oxygen means a higher
partial pressure if all else stays equal.

Oxygen concentrators are nothing new. Only the concept of making them
truly portable is new. My wive needs oxygen for the duration of our frequent
trips to Denver, and I can tell you from experience that either pure oxygen or
oxygen from a concentrator serve equally fine to increase her oxygen sats.
Flying would be no different.

By the way, this concentrator technology is becoming so common that even
tire shops are rapidly getting it, so they can charge you more for putting
nitrogen in your tires rather than ordinary air.


Vaughn

Looking a bit more, I still don't see these units being recommended for
civil aircraft, but the specifications look fairly good. They more
typically require 40 to 60 watts to get 5 liters per minute flow of 80%
to 90% oxygen at several psi. Prices vary from $500 for reconditioned
units to $1000 to $4000 for new ones. Some of them are even designed
to fill high pressure tanks at home, if you prefer to stick with a
tank. If I were a frequent high flyer, I would persue this some more.

tom

> This is done in military helicopters--oxygen for the crew and dry nitrogen
> for the air space in the fuel tanks. By now, it is almost certainly done in
> some other aircraft as well.
>
> I have believed for some that this would be a good primary method to supply
> oxigen in light civil aircraft--with "candles" such as the airlines use as
> emergency backup.
>
> Try a Google or WebCrawler search with the argument: oxygen + concentrator
> (or) oxygen + concentrator + aircraft
>
> Peter

If you evaporate water from a salt+water solution, does the
concentration of salt increase? Sure it does.

Think of nitrogen as the water, and the oxygen as the salt.



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.
>
> Pure O2 in a tank, delivered to a mask to displace some of
> the ambient air and replace the displaced portion certainly
> raises the O2 partial pressure. But an O2 concentrator
> doesn't seem to have a pressure function or am I missing
> something?
>
>
>
> "Vaughn Simon" > wrote in
> message
> ...
> |
> | "Bill Denton" > wrote in message
> | t...
> | > O2 Concentrators work by removing nitrogen from the
> ambient air, leaving the
> | > oxygen, which comprises 21% of the air.
> | >
> | > 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.
> | >
> | > So, would a concentrator even provide any benefits?
> |
> | Yes, because you are breathing air with a higher
> concentration of oxygen,
> | wich will result in higher blood oxygen saturation levels.
> My wife has used
> | one of those battery operated concentrators for commercial
> air travel with great
> | results. They are a fairly new product, and cost around
> 5 AMUs.
> |
> | To solve the power problem, it would be theoretically
> possible to build a
> | concentrator with a belt-driven compressor as a permanent
> installation in a
> | aircraft. It would not be cheap, but it would be far
> cheaper than
> | pressurization. Perhaps some clever engineer could build
> a dual vacuum
> | pump/compressor to bolt on the same engine pad as your
> vacuum pump. With an
> | installation like that, you could afford to fly with
> oxygen always and enjoy the
> | better eyesight and quicker thinking that comes with 100%
> blood oxygen
> | saturation.
> |
> | Vaughn
> |
> |

There certainly won't be any cost advantage unless the system receives a lot
of use.

Peter

> Looking a bit more, I still don't see these units being recommended for
> civil aircraft, but the specifications look fairly good. They more
> typically require 40 to 60 watts to get 5 liters per minute flow of 80%
> to 90% oxygen at several psi. Prices vary from $500 for reconditioned
> units to $1000 to $4000 for new ones. Some of them are even designed
> to fill high pressure tanks at home, if you prefer to stick with a
> tank. If I were a frequent high flyer, I would persue this some more.
>
> tom
>
> > This is done in military helicopters--oxygen for the crew and dry
nitrogen
> > for the air space in the fuel tanks. By now, it is almost certainly
done in
> > some other aircraft as well.
> >
> > I have believed for some that this would be a good primary method to
supply
> > oxigen in light civil aircraft--with "candles" such as the airlines use
as
> > emergency backup.
> >
> > Try a Google or WebCrawler search with the argument: oxygen +
concentrator
> > (or) oxygen + concentrator + aircraft
> >
> > Peter
>

"Peter Dohm" > wrote in message
...
> There certainly won't be any cost advantage unless the system receives a
> lot
> of use.
>
> Peter

If you're an O2 user, think of the convenience. No more having to pick FBO's
and airports based on O2 availability. Also, consider that you'd probably
use the concentrator on many flights in the 6-12k ft region, and will feel
better after those flights than if you had a bottled O2 system and didn't
use it because you were hoarding O2 for when you "really" need it.

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

You can't remove N without increasing the concentration of O, unless you
intentionally replace the N with something other than O. So, yes...you're
right that if you don't increase the concentration of O, the partial
pressure of O will stay the same. But you'd have to go to extra trouble to
do that. Simply removing N will necessarily increase the concentration of
O.

> Pure O2 in a tank, delivered to a mask to displace some of
> the ambient air and replace the displaced portion certainly
> raises the O2 partial pressure. But an O2 concentrator
> doesn't seem to have a pressure function or am I missing
> something?

The cannulas and masks used in general aviation don't "have a pressure
function". They work simply by adding O to the stream of air being
breathed.

If you have a mix of N and O, you can increase the concentration of O either
by adding O or removing N. Conventional oxygen systems work by doing the
former, while the concentrator discussed here does the latter. In either
case, the result is the same.

Pete

> > There certainly won't be any cost advantage unless the system receives a
> > lot
> > of use.
> >
> > Peter
>
> If you're an O2 user, think of the convenience. No more having to pick
FBO's
> and airports based on O2 availability. Also, consider that you'd probably
> use the concentrator on many flights in the 6-12k ft region, and will feel
> better after those flights than if you had a bottled O2 system and didn't
> use it because you were hoarding O2 for when you "really" need it.
>
>
I agree.

Peter

Hmm ... 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.

The main reason for cabin pressurization is to provide enough oxygen
for crew and passengers without the need for individual oxygen
systems. However, if you can economically enrich the cabin atmosphere
with oxygen using oxygen concentrators, you could keep the cabin
pressure much lower--possibly even at the ambient outside pressure, up
to certain altitudes. This might be a lot less expensive to engineer
and maintain than full pressurization systems. American astronauts
have long used this type of system.

You could also use the nitrogen from the system to fill fuel tanks, to
reduce the risk of fire, evaporation, condensation, etc.

--
Transpose mxsmanic and gmail to reach me by e-mail.

Recently, Larry Dighera > posted:

> On Sat, 02 Dec 2006 11:42:08 GMT, "Neil Gould"
> > wrote in
> >:
>
>> At 12v, 100w = 8.3 amps; 400w = 33.2 amps (half those for 24v
>> systems). That's a lot of juice to draw.
>
> I thought about that too, but IIRC cigar lighters are fused at 10A,
> and the pilot alone can operate on oxygen up to 15,000' for thirty
> minutes without oxygen for passengers:
>
As a rule of thumb, the safety margin in many electrical circuits is
around 66% (2/3) of the fuse/breaker rating. A cigar lighter using the
heating element draws a certain amount of current for a relatively short
time. Putting a > 80% full-time load on that circuit would not be wise,
IMO. I haven't run accross any 50 amp breakers on the panels in the GA
plane that I fly.

Another consideration, your alternator will have to carry that load *plus*
everything else in the plane and still supply regenerative power to the
battery to be practical and reliable. So, if someone wants to go this
route, several aspects of the plane's electrical system might need some
attention.

Neil

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...







"Peter Duniho" > wrote in message
...
> "Jim Macklin" > wrote in message
> ...
> > If you don't increase the concentration of oxygen, but are
> > merely removing N, the partial pressure of the oxygen will
> > not increase.
>
> You can't remove N without increasing the concentration of O, unless you
> intentionally replace the N with something other than O. So, yes...you're
> right that if you don't increase the concentration of O, the partial
> pressure of O will stay the same. But you'd have to go to extra trouble
to
> do that. Simply removing N will necessarily increase the concentration of
> O.
>
> > Pure O2 in a tank, delivered to a mask to displace some of
> > the ambient air and replace the displaced portion certainly
> > raises the O2 partial pressure. But an O2 concentrator
> > doesn't seem to have a pressure function or am I missing
> > something?
>
> The cannulas and masks used in general aviation don't "have a pressure
> function". They work simply by adding O to the stream of air being
> breathed.
>
> If you have a mix of N and O, you can increase the concentration of O
either
> by adding O or removing N. Conventional oxygen systems work by doing the
> former, while the concentrator discussed here does the latter. In either
> case, the result is the same.
>
> Pete
>
>

"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).

--
Transpose mxsmanic and gmail to reach me by e-mail.

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/index.phtml?nav_id=26&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/index.phtml?nav_id=26&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?

--
Transpose mxsmanic and gmail to reach me by e-mail.

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

>Larry Dighera writes:
>
>> Up to a point:
>>
>> http://www.mountainhighoxygen.com/index.phtml?nav_id=26&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).
for Email, make the obvious change in the address.

> 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

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

Think of the concentrator as a splitter.. it sends the nitrogen down one
tube (a waste port).. and the remaining oxygen down the supply port to
the pilot/patient/person whatever.

You arent creating anything new, or creating mass.... (so no physical
laws are broken)

but you ARE directing a stream of concentrated, nearly pure oxygen down
a supply tube at flow rates of up to 3-4 liters per minute.

you ARE increasing the overall inspired fraction of oxygen to the person
who inhales this gas stream. The oxygen doesnt know and doesnt carehow
it got there. Doesnt matter if its concentrated from an ambient air
source at near ambient pressure (conentrator)..... or if its
cryodistilled, vaporized, compressed to 2200 psi, then stored, shipped,
reduced to 25-50 psi working pressure before its returned to near
ambient pressure (tank).

Dave

Ron Natalie wrote:
> 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.


Working in very round numbers, if you'd accept the total pressure of the
atmosphere at sea level to be 15 psi, the partial pressure of oxygen would be 3
psi (20% of 15). At around 18,000 feet, the total atmospheric pressure is cut
in half, so the partial pressure of oxygen at that altitude would be about 1.5
psi. You need to come up with another 1.5 psi of oxygen to bring it up to an
equivalence with what we breath a sea level.

I'm not exactly sure how a concentrator would work since I'm foggy about its
operation. Even dealing with bottled oxygen, you don't get to assume a simple
mathematical relationship because the cannula just adds pure O2 to what blows up
your nose... but it doesn't exclude ambient air.

I'm finding this whole thread confusing. Maybe I need a hit of O2?



--
Mortimer Schnerd, RN
mschnerdatcarolina.rr.com

Larry Dighera writes:

> And if I recall correctly, above 25,000' a pressure mask or cabin
> pressurization are required due to human physiology.

The physiological requirements for whole-body pressurization are much
less stringent than those for oxygen, but there is a lot of individual
variation. Some people are so sensitive to altitude that they can
become sick during a ride in an ordinary airliner at 8000' cabin
altitude. Some will get sick just from visiting Denver. Others
(usually after a period of gradual adaptation) are still okay at
28,000 feet.

> 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.

This is a matter of oxygen, not pressure. With plenty of oxygen,
20,000 feet will not necessarily do any harm at all, depending on the
individual. People with CV and respiratory problems should avoid high
altitudes, though.

--
Transpose mxsmanic and gmail to reach me by e-mail.

Mortimer Schnerd, RN schrieb:

> I'm finding this whole thread confusing. Maybe I need a hit of O2?

It is confusing because (nearly) everybody uses ambiguous words (1) and
nobody's cared so far to describe the setup which he assumes (2).

1) concentration, amount, pressure, when all which matters is partial
pressure of O2.

2) At which point does the concentrator extract N2 from the air and
where does he blow the "O2-concentrated" air? How is that "concentrated"
O2 provided: Via a Cannula which adds a stream of O2 to inhaled ambient
air? Via a closed mask? Into the cabin as a whole? etc.

Stefan

Stefan wrote:

> 2) At which point does the concentrator extract N2 from the air and
> where does he blow the "O2-concentrated" air? How is that "concentrated"
> O2 provided: Via a Cannula which adds a stream of O2 to inhaled ambient
> air? Via a closed mask? Into the cabin as a whole? etc.

The concentrator provides between 85 to 95 % oxygen (depending on
flow rate) at essentially the ambient pressure (at least at sea level).

The thing uses a compressor internally to bring the pressure up to about
20 PSI to force it through the filters that do the separation. The unit
functions pretty well up to 18,000' according to stuff I've seen (you
really want a pressure system after that anyhow). Part of the issue
is they do tend to operate at higher temperatures as the pump has to
work harder.

Dave S wrote:
> 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".


Why are we having this argument? Is it not true that people use
concentrators at altitude in unpressurized planes and they don't pass
out? If that is the case, and it is my understanding that it is, then
they must work. So what is the argument about?


--
Chris W
KE5GIX

"Protect your digital freedom and privacy, eliminate DRM,
learn more at http://www.defectivebydesign.org/what_is_drm"

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"Chris W" > wrote in message
...
>
> Why are we having this argument? Is it not true that people use concentrators
> at altitude in unpressurized planes and they don't pass out? If that is the
> case, and it is my understanding that it is, then they must work. So what is
> the argument about?

It beats me. I have sat in a 10,000 foot cabin pressure in an airliner and
monitored my wife's blood ox sats with and without the concentrator. I can tell
you for sure that a concentrator works just fine under that situation.

Vaughn

I believe airline cabin pressure is somewhat below 10,000 ft...



"Vaughn Simon" > wrote in message
...
>
> "Chris W" > wrote in message
> ...
> >
> > Why are we having this argument? Is it not true that people use
concentrators
> > at altitude in unpressurized planes and they don't pass out? If that is
the
> > case, and it is my understanding that it is, then they must work. So
what is
> > the argument about?
>
> It beats me. I have sat in a 10,000 foot cabin pressure in an
airliner and
> monitored my wife's blood ox sats with and without the concentrator. I
can tell
> you for sure that a concentrator works just fine under that situation.
>
> Vaughn
>
>

Chris W writes:

> Why are we having this argument?

Because this is USENET.

> Is it not true that people use
> concentrators at altitude in unpressurized planes and they don't pass
> out? If that is the case, and it is my understanding that it is, then
> they must work. So what is the argument about?

See above.

--
Transpose mxsmanic and gmail to reach me by e-mail.

Bill Denton writes:

> I believe airline cabin pressure is somewhat below 10,000 ft...

It's 8000 feet at most, IIRC. Still, it's not the cabin pressure that
matters, it's the oxygen content. With an oxygen-enriched atmosphere,
you can go a lot higher in cabin pressure for a lot longer.

--
Transpose mxsmanic and gmail to reach me by e-mail.

> Ron Natalie wrote:
> > 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.
>
>
> Working in very round numbers, if you'd accept the total pressure of the
> atmosphere at sea level to be 15 psi, the partial pressure of oxygen would
be 3
> psi (20% of 15). At around 18,000 feet, the total atmospheric pressure is
cut
> in half, so the partial pressure of oxygen at that altitude would be about
1.5
> psi. You need to come up with another 1.5 psi of oxygen to bring it up to
an
> equivalence with what we breath a sea level.
>
> I'm not exactly sure how a concentrator would work since I'm foggy about
its
> operation. Even dealing with bottled oxygen, you don't get to assume a
simple
> mathematical relationship because the cannula just adds pure O2 to what
blows up
> your nose... but it doesn't exclude ambient air.
>
> I'm finding this whole thread confusing. Maybe I need a hit of O2?
>
> --
> Mortimer Schnerd, RN
> mschnerdatcarolina.rr.com
>
This thread has certainly been "interesting" and Mortimer may have stated
the solution to a lot of the strangest and most confusing posts: "...the
cannula just adds pure O2 to what blows up
your nose... but it doesn't exclude ambient air."

We are not talking about a sealed system. Whether an aircraft is pressured
or not, air is forced to flow through the cabin--whether pumped or simply
allowed to flow in at some point where ram pressure is available, and
subsequently vented back to the outside atmosphere.

Any concentrator, whether portable or installed, will take a portion of the
air stream (possibly from the cabin, but not necessarily) and strip off the
O2 by means of a zeolite bed. The operation of the concentrator is
cyclic--it vents its waste gasses through an outlet, it vents the
concentrated gas (oxygen) to the oxigen masks or canulas, and it pumps in
more air. It does not take air from the pilot's nose and attempt to put it
back as oxygen, but takes a small part of the overall air stream from some
other location and provides locally concentrated oxygen to the pilot (and
passengers)--which inceases the locally available partial pressure of oxygen
as Ron and Mortimer have each stated.

In the case of an installed concentrator, which would have more power and
volume available, the flow can be smoothed and regulated and/or dry nitrogen
can be concentrated from the waste gasses and supplied to the fuel tank(s).
BTW, there are a lot of nitrogen concentrators in use which dump the
resulting oxigen as part of the waste gas stream--and the ones used in
aircraft are probably a minority.

Peter

> So what is the argument about?

It's about why, or how, it works.

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.

> Working in very round numbers, if you'd accept the total pressure of the
> atmosphere at sea level to be 15 psi, the partial pressure of oxygen would be 3
> psi (20% of 15). At around 18,000 feet, the total atmospheric pressure is cut
> in half, so the partial pressure of oxygen at that altitude would be about 1.5
> psi. You need to come up with another 1.5 psi of oxygen to bring it up to an
> equivalence with what we breath a sea level.

Right, and that comes from the treated air being compressed by the
surrounding atmosphere.

Think of it this way - you have a jar full of sand and salt. Sand
concentration is (say) 50%. You run water through that jar, dissolving
the salt away. Now you have a jar that's HALF full of sand (and half
full of nothing). That sand isn't going to spread itself evenlty
throughout the jar - there is nothing magically holding the sand grains
apart (unless you take it to a rock concert). The sand grains all fall
to the bottom. The bottom of the jar is now more concentrated - 100%
sand. The top of the jar is of no consequence.

Similarly, when nitrogen is removed, the =purity= of the oxygen
increases (it used to be contaminated with nitrogen, but isn't any more.
However, there is nothing to the oxygen molecules as far apart as they
were before. The nitrogen that used to get in their way is gone. The
oxygen molecules get crushed together by the surrounding ambient
pressure. THAT increases the partial pressure.

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.

On Dec 3, 5:05 am, Mxsmanic > wrote:
> Larry Dighera writes:
> > And if I recall correctly, above 25,000' a pressure mask or cabin
> > pressurization are required due to human physiology.The physiological requirements for whole-body pressurization are much
> less stringent than those for oxygen, but there is a lot of individual
> variation. Some people are so sensitive to altitude that they can
> become sick during a ride in an ordinary airliner at 8000' cabin
> altitude. Some will get sick just from visiting Denver. Others
> (usually after a period of gradual adaptation) are still okay at
> 28,000 feet.
>
> > 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.This is a matter of oxygen, not pressure. With plenty of oxygen,
> 20,000 feet will not necessarily do any harm at all, depending on the
> individual. People with CV and respiratory problems should avoid high
> altitudes, though.
>


You're not quite right about it being only a partial pressure of
oxygen issue. There are cases of for example brain swelling that is
absolute pressure, not pp O2, related. Accept for example the fact that
your blood is nitrogen saturated -- it has the same partial pressure of
N2 as ambient at sea level. Rapid increases in altitude can result in
bends like symptoms. Blood is very capable of outgassing. I don't have
the data in front of me, but I thnk you'd have a very difficult time at
3 psi absolute even if it was all oxygen (and that's it partial
pressure at sea level.) I'd say most of the population would have a
difficult time at 20,000 feet even with 3 PSI partial pressure of
oxygen. I'm not interested in providing citations, but those interested
could look at the way people spend time learning to live at altitute
before climbing 20000 footers. You'll find people who live high in the
mountains in South America typically are very deep chested and run
hemoglobin levels quite a lot higher than we near sea level dwelling
creatures do as part of their adaption to high altitude living.


> --
> Transpose mxsmanic and gmail to reach me by e-mail.

Tony writes:

> You're not quite right about it being only a partial pressure of
> oxygen issue. There are cases of for example brain swelling that is
> absolute pressure, not pp O2, related. Accept for example the fact that
> your blood is nitrogen saturated -- it has the same partial pressure of
> N2 as ambient at sea level. Rapid increases in altitude can result in
> bends like symptoms. Blood is very capable of outgassing.

Presumably GA aircraft don't often loiter at really high altitudes. I
get the impression that even 15,000 feet is high for a GA aircraft.

Nitrogen can be a problem, but breathing pure oxygen (or nitrogen-poor
air) for an hour or two in advance of the ascent can help (not very
practical for air travel, I admit, even though it worked for the
SR-71).

HACE is apparently more linked to oxygen than absolute air pressure,
although I'm not sure why (it seems like it would be a pressure issue,
not an oxygenation issue).

> I don't have the data in front of me, but I thnk you'd have a very
> difficult time at 3 psi absolute even if it was all oxygen (and that's
> it partial pressure at sea level.)

Actually, Apollo astronauts got by easily with 4.8 psi and pure
oxygen.

> I'd say most of the population would have a
> difficult time at 20,000 feet even with 3 PSI partial pressure of
> oxygen. I'm not interested in providing citations, but those interested
> could look at the way people spend time learning to live at altitute
> before climbing 20000 footers. You'll find people who live high in the
> mountains in South America typically are very deep chested and run
> hemoglobin levels quite a lot higher than we near sea level dwelling
> creatures do as part of their adaption to high altitude living.

All of this, though, is due to the need for oxygen. Provide the
oxygen, and the requirements in terms of absolute pressure are much
more modest. You can't live in a vacuum, but you can live at
pressures much lower than sea level indefinitely.

--
Transpose mxsmanic and gmail to reach me by e-mail.

"Bill Denton" > wrote

>I believe airline cabin pressure is somewhat below 10,000 ft...

It can be set at anything the pilots want.

It is not a uncommon practice to raise the cabin altitude on a long red-eye, to
give the cabin crew a little break from working the passengers.
--
Jim in NC

"Vaughn Simon" > wrote

> It beats me. I have sat in a 10,000 foot cabin pressure in an airliner
> and monitored my wife's blood ox sats with and without the concentrator. I
> can tell you for sure that a concentrator works just fine under that
> situation.

Do you recall the sats for her, with and without the concentrator?
--
Jim in NC

"Morgans" > wrote in message
...
>
> "Vaughn Simon" > wrote
>
>> It beats me. I have sat in a 10,000 foot cabin pressure in an airliner
>> and monitored my wife's blood ox sats with and without the concentrator. I
>> can tell you for sure that a concentrator works just fine under that
>> situation.
>
> Do you recall the sats for her, with and without the concentrator?

Assuming the highest portion of a typical airline flight: Without the
machine they slip down into the low to mid 80's. With the machine on, we get in
the high 90's. At sea level (home, no oxygen) her sats are around 93. FYI:
Anything below 90 is considered a justification for supplemental oxygen.

She has a lung problem and we are lucky to live at sea level.

Vaughn

MX wrote = Actually, Apollo astronauts got by easily with 4.8 psi and
pure
oxygen.


Would you care to explain how the Apollo experience, with very fit men
doing well on 4.8 psi PP O2 is in any way related to my assertion that
you, or the general population, would have difficulty surviving in a
pure oxygen atmosphere of 3 psia?

Preconditioned breathing is of course a way to avoid psudo bend and
outgassing problems, but as you correctly point out, it is not in
general done by those of us who fly, so my concerns are still valid.

The hemoglobin dissociation curve is working against your claim. I am
reminded of a friend who unfortunately has a brain tumor that will be
the cause of her death. She says "I don't let reality interfere with my
day."

You do appear to be a little misinformed about human physiology, but
then again, many of us are.


On Dec 3, 12:46 pm, Mxsmanic > wrote:
> Tony writes:
> > You're not quite right about it being only a partial pressure of
> > oxygen issue. There are cases of for example brain swelling that is
> > absolute pressure, not pp O2, related. Accept for example the fact that
> > your blood is nitrogen saturated -- it has the same partial pressure of
> > N2 as ambient at sea level. Rapid increases in altitude can result in
> > bends like symptoms. Blood is very capable of outgassing.Presumably GA aircraft don't often loiter at really high altitudes. I
> get the impression that even 15,000 feet is high for a GA aircraft.
>
> Nitrogen can be a problem, but breathing pure oxygen (or nitrogen-poor
> air) for an hour or two in advance of the ascent can help (not very
> practical for air travel, I admit, even though it worked for the
> SR-71).
>
> HACE is apparently more linked to oxygen than absolute air pressure,
> although I'm not sure why (it seems like it would be a pressure issue,
> not an oxygenation issue).
>
> > I don't have the data in front of me, but I thnk you'd have a very
> > difficult time at 3 psi absolute even if it was all oxygen (and that's
> > it partial pressure at sea level.)Actually, Apollo astronauts got by easily with 4.8 psi and pure
> oxygen.
>
> > I'd say most of the population would have a
> > difficult time at 20,000 feet even with 3 PSI partial pressure of
> > oxygen. I'm not interested in providing citations, but those interested
> > could look at the way people spend time learning to live at altitute
> > before climbing 20000 footers. You'll find people who live high in the
> > mountains in South America typically are very deep chested and run
> > hemoglobin levels quite a lot higher than we near sea level dwelling
> > creatures do as part of their adaption to high altitude living.All of this, though, is due to the need for oxygen. Provide the
> oxygen, and the requirements in terms of absolute pressure are much
> more modest. You can't live in a vacuum, but you can live at
> pressures much lower than sea level indefinitely.
>
> --
> Transpose mxsmanic and gmail to reach me by e-mail.

"Richard Riley" > wrote in message
...
> On Sun, 03 Dec 2006 20:32:03 GMT, "Vaughn Simon"
>
> Do airliners have a power outlet, or are you running it on batteries?

More and more airliners have power outlets, but you can't depend on having
one at your seat so we bring batteries. We rent the machine, and I believe that
we were getting 2 or 3 hours on a battery.

Vaughn

Tony writes:

> Would you care to explain how the Apollo experience, with very fit men
> doing well on 4.8 psi PP O2 is in any way related to my assertion that
> you, or the general population, would have difficulty surviving in a
> pure oxygen atmosphere of 3 psia?

Fitness has no effect on susceptibility to altitude sickness and
hypoxia. Adaptations are slow to occur and readily lost and rarely
practical, even for astronauts. However, a pure oxygen atmosphere at
4.8 psi apparently works just fine, for anyone in normal health.

The Apollo spacecraft were regulated to between 4.8 and 5.0 psi,
roughly, as I recall. Spacesuits were set to even lower pressures,
around 3.8 psi.

--
Transpose mxsmanic and gmail to reach me by e-mail.

On Dec 3, 6:02 pm, Mxsmanic > wrote:
> Tony writes:
> > Would you care to explain how the Apollo experience, with very fit men
> > doing well on 4.8 psi PP O2 is in any way related to my assertion that
> > you, or the general population, would have difficulty surviving in a
> > pure oxygen atmosphere of 3 psia?



Fitness has no effect on susceptibility to altitude sickness and
> hypoxia. Adaptations are slow to occur and readily lost and rarely
> practical, even for astronauts. However, a pure oxygen atmosphere at
> 4.8 psi apparently works just fine, for anyone in normal health.

Fitness has no effect?? For someone who writes well enough to sometimes
sound credible, you ruin it all by making statements like that.

Now, almost 5 psia of O2 is a long way from 3 psia -- which was my
statement.

Fitness, with good O2 exchange, means nearly EVERYHTHING with respect
to operating in low oxygen environments.

I fully accept that someone who isn't rated can make meaningful
contributions to this group, but don't continue to make statements that
make others question your credibility, it makes others question your
valid statements.

Oh well, I'm outta here.




>
> The Apollo spacecraft were regulated to between 4.8 and 5.0 psi,
> roughly, as I recall. Spacesuits were set to even lower pressures,
> around 3.8 psi.
>
> --
> Transpose mxsmanic and gmail to reach me by e-mail.

"Chris W" > wrote in message
...
> Why are we having this argument?

Because this is Usenet. We (and I include myself) have a pathological need
to point out the errors in even the most obviously ignorant post. :)

That said, I use the term "ignorant" in only the purest sense of the word,
and it's possible that Bill Denton may actually learn something. There's no
need for his ignorance to be perpetual, nor is it clear to me that we are
really so much arguing about this as we are working through one person's
misunderstandings.

> Is it not true that people use concentrators at altitude in unpressurized
> planes and they don't pass out? If that is the case, and it is my
> understanding that it is, then they must work. So what is the argument
> about?

Knowing something works is not necessarily the same as understanding why or
how it works. To draw a parallel, consider the question glide angle (and by
extension, distance). It's somewhat non-intuitive to understand that glide
angle is constant as weight varies, and that the only thing that weight
changes is the speed at which the best glide angle occurs. You might
witness an "argument" as a person struggles through understanding the why
and how of that.

I should know...I've been there, on the ignorant side of that "argument".
:) Of course, just when I thought I had it all figured out, someone came
along and explained to me that it turns out that glide angle *is* affected
to a small degree by weight. Just not to the degree one might naively
assume.

Anyway, given that the question involves pressures, volumes, open systems,
closed systems, and physiology, it's not too surprising that at least one
person has formed the wrong intuitive idea of the situation. Hopefully, we
can just "argue" the truth into him. :)

Pete

tom wrote:
> Does anyone use an oxygen concentrator to supply pilot and passengers
> in a light plane flying over 14000 feet? A quick google did not turn
> up anything but home units and a recent ruling that they can be used on
> commercial airlines, but I did not find anything about their use on
> private planes.
>
> They don't require more than about 100 watts, so an aircraft electrical
> system could keep them going as long as the engine was running.
> Internal batteries would keep it alive in an emergency.
>
> Seems like a nice solution to elimination of messing with refilling
> tanks.
>
> tom

Hi Tom,

I'm a pilot and I sell concentrators. I'm not too sure they will work
well at 14000 feet. The new (expensive) little ones are pretty
marginal at best.


tom wrote:
> Does anyone use an oxygen concentrator to supply pilot and passengers
> in a light plane flying over 14000 feet? A quick google did not turn
> up anything but home units and a recent ruling that they can be used on
> commercial airlines, but I did not find anything about their use on
> private planes.
>
> They don't require more than about 100 watts, so an aircraft electrical
> system could keep them going as long as the engine was running.
> Internal batteries would keep it alive in an emergency.
>
> Seems like a nice solution to elimination of messing with refilling
> tanks.
>
> tom

"Vaughn Simon" > wrote

> She has a lung problem and we are lucky to live at sea level.

I'm glad you are able to deal with it satisfactorily.
--
Jim in NC

Tony writes:

> Fitness has no effect??

Yes.

> For someone who writes well enough to sometimes
> sound credible, you ruin it all by making statements like that.

I'm sorry if it sounds incredible. I did the research, and that was
the result.

> Fitness, with good O2 exchange, means nearly EVERYHTHING with respect
> to operating in low oxygen environments.

No, it does not. You can be in good health, or great health, but it
doesn't make any difference. Even Olympic champions will yield to
altitude sickness just as often as normal people, and their
vulnerability is just as unpredictable.

Someone who is truly in poor health with respiratory, cardiac, or some
other problems may be more sensitive to hypoxia at altitude, but being
in robust health and physically fit doesn't help. In fact, many of
these problems don't hurt, either, except insofar as they make the
effects of hypoxia more dangerous.

> I fully accept that someone who isn't rated can make meaningful
> contributions to this group, but don't continue to make statements that
> make others question your credibility, it makes others question your
> valid statements.

Others can do the same research I do, and they can reach the same
conclusions. Or they can spend their time on personal attacks. The
former is a learning experience; the latter is a waste of time,
especially when I'm the target.

--
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GomezAddams wrote:
> Hi Tom,
>
> I'm a pilot and I sell concentrators. I'm not too sure they will work
> well at 14000 feet. The new (expensive) little ones are pretty
> marginal at best.
>
There have been tests of portable units and the major issue with
them going up in altitude is not that they don't work, but they
get a lot because the compressor works harder.

> There have been tests of portable units and the major issue with
> them going up in altitude is not that they don't work, but they
> get a lot because the compressor works harder.

That is really an interesting point. Prior to this thread--I had never
given any thought to the possibility of anyone using a portable concentrator
in the cabin of an aircraft, as my interest had been to eliminate the use of
refillable bottles for normal use. I had simply presumed that the
compressor(s) would be driven directly by the engine(s) and that any
necessary intercooling would be provided prior to the concentrator unit; or
alternatively that a purpose build self contained unit would be installed.
Therefore, this thread has been something of a revelation.

Peter

On 1 Dec 2006 22:28:10 -0800, "tom" > wrote:

>Does anyone use an oxygen concentrator to supply pilot and passengers
>in a light plane flying over 14000 feet? A quick google did not turn
>up anything but home units and a recent ruling that they can be used on
>commercial airlines, but I did not find anything about their use on
>private planes.
>
>They don't require more than about 100 watts, so an aircraft electrical
>system could keep them going as long as the engine was running.
>Internal batteries would keep it alive in an emergency.

Changing subjects slightly - what kind of maintenance is required on
an oxygen concentrator? Does the zeolite need to be replaced every so
often? I scanned the webpages of a few manufacturers, and it appears
to be a relatively maintenance free product.

Anyway, it seems an interesting concept to use an O2 concentrator vs
bottle in the plane.

Nathan Young writes:

> Changing subjects slightly - what kind of maintenance is required on
> an oxygen concentrator? Does the zeolite need to be replaced every so
> often? I scanned the webpages of a few manufacturers, and it appears
> to be a relatively maintenance free product.

Air filters need to be changed periodically. The zeolite lasts
indefinitely.

--
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"Morgans" > wrote in message
...
>
> "Bill Denton" > wrote
>
>>I believe airline cabin pressure is somewhat below 10,000 ft...
>
> It can be set at anything the pilots want.

Not true, it is limited by the amount of differential pressure the plane can
take.

It is normal to operate at a cabin pressure of 8,000 ft and a pressure
differential across the aircraft skin is normally designed not to exceed 8-9
psi.

As far as partial pressures are concerned, its the partial pressure in the
lungs that matters.

At sea level the partial pressure of oxygen in the atmosphere is 160 mm Hg
yet in the lungs it is only 103 mm Hg. At 10,000 ft that drops to 55 mm Hg
which is considered the minimum for normal operations. Above cabin
altitudes of 10,000 ft oxygen needs to be added to the pilots air supply.
The oxygen which is added should be enough to maintain a pressure of oxygen
in the lungs (alveolar partial pressure) of 103 mm Hg.

At lower levels less oxygen will need to be added but as altitude increases
more will need to be added. A stage will be reached when the 100% oxygen is
required to maintain the 103 mm Hg. This is reached at about 33,700 ft.

After this whilst breathing 100% oxygen one can continue to operate
normally with an alveolar partial pressure of 55 mm Hg (equivalent to
breathing air at 10,000 ft). This is reached at 40,000 ft. From here
oxygen needs to be supplied under pressure.

Summary

Upto 10,000 ft air only
10,000 - 33,700 ft Oxygen/air mix
33,700 - 40,000 ft 100% oxygen
40,000 + 100% Oxygen under pressure

"Chris" > wrote

> Not true, it is limited by the amount of differential pressure the plane can
> take.

Well, duh.
--
Jim in NC

Morgans wrote:
>
> "Chris" > wrote
>
>> Not true, it is limited by the amount of differential pressure the
>> plane can take.
>
> Well, duh.

Well said :)

--
Chris W
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>
> >Does anyone use an oxygen concentrator to supply pilot and passengers
> >in a light plane flying over 14000 feet? A quick google did not turn
> >up anything but home units and a recent ruling that they can be used on
> >commercial airlines, but I did not find anything about their use on
> >private planes.
> >
> >They don't require more than about 100 watts, so an aircraft electrical
> >system could keep them going as long as the engine was running.
> >Internal batteries would keep it alive in an emergency.
>
> Changing subjects slightly - what kind of maintenance is required on
> an oxygen concentrator? Does the zeolite need to be replaced every so
> often? I scanned the webpages of a few manufacturers, and it appears
> to be a relatively maintenance free product.
>
> Anyway, it seems an interesting concept to use an O2 concentrator vs
> bottle in the plane.
>
>
There is some periodic maintenance of the zeolite "beds", although I don't
know exactly what or how. And of course that is in additional to the
periodic inspection of pumps, valves, filters, etc. However, there is
little question that the O2 concentrators are both lighter and more
economical than bottled O2 when used extensively or frequently.

Peter

On Sat, 02 Dec 2006 10:38:45 -0500, in
>, Peter R. wrote:
> I flew at 14,000 once with O2 for myself and co-pilot only and the boy in
> the back seat vomited into a bag about halfway into the trip.

I've never encountered that as a symptom of altitude induced hypoxia...
Seems that the only thing that I've encountered come to think of it is
that the people that are not on O2 just get sleepy and quit bothering me...

> > I flew at 14,000 once with O2 for myself and co-pilot only and the boy
in
> > the back seat vomited into a bag about halfway into the trip.
>
> I've never encountered that as a symptom of altitude induced hypoxia...
> Seems that the only thing that I've encountered come to think of it is
> that the people that are not on O2 just get sleepy and quit bothering
me...

I used to think that as well, but very reliable sources have told me that
headaches and nausea are also frequently encountered--although not as
commonly as sleepiness.

Peter

Grumman-581 writes:

> I've never encountered that as a symptom of altitude induced hypoxia...

Vomiting alone sounds more like airsickness.

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Peter Dohm writes:

> I used to think that as well, but very reliable sources have told me that
> headaches and nausea are also frequently encountered--although not as
> commonly as sleepiness.

A headache is a very common symptom of altitude sickness, although
headaches have many other causes as well. Vomiting can be a symptom
of altitude sickness, but it can also be due to motion sickness, and
vomiting, too, has many other causes. Vomiting by itself may or may
not be altitude sickness; it's not a very specific symptom.

--
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Chris wrote:
> "Morgans" > wrote in message
> ...
>> "Bill Denton" > wrote
>>
>>> I believe airline cabin pressure is somewhat below 10,000 ft...
>> It can be set at anything the pilots want.
>
> Not true, it is limited by the amount of differential pressure the plane can
> take.

The certification requirement is that the cabin altitude be no
higher than 8,000 feet. On later aircraft, the pressurization
is pretty much a "set the destination altitude" and don't mess
with it. Back in the old days of flight engineers it took a
bit more management.

The new 787 I believe is being designed with both a lower cabin
altitude and also increased humidity for passenger comfort.

"Chris" > wrote in message
...
snip

>
> Upto 10,000 ft air only
> 10,000 - 33,700 ft Oxygen/air mix
> 33,700 - 40,000 ft 100% oxygen
> 40,000 + 100% Oxygen under pressure
>
>

I flew fighters for the Air Force (F-4E) and I recal going to pressure
breathing at about 25,000 feet cabin altitude. This was an emergency only
because the cabin pressure never got this high. I also recall a rule to not
go over 50,000 feet because of blood boiling (bends) IF the cabin pressure
was lost at greater than 50,000 feet.


Danny Dot
>

"Peter Duniho" > wrote in message
...
snip

> I should know...I've been there, on the ignorant side of that "argument".
> :) Of course, just when I thought I had it all figured out, someone came
> along and explained to me that it turns out that glide angle *is* affected
> to a small degree by weight. Just not to the degree one might naively
> assume.
>

OK, I need to know how weight changes glide angle. I have a Masters in
Aerospace Engineering and thought it was not.

Danny Dot

"Danny Dot" > wrote:
> "Peter Duniho" > wrote:
>> I should know...I've been there, on the ignorant side of that
>> "argument".
>> :) Of course, just when I thought I had it all figured out, someone
>> :came
>> along and explained to me that it turns out that glide angle *is*
>> affected to a small degree by weight. Just not to the degree one
>> might naively assume.
>>
>
> OK, I need to know how weight changes glide angle. I have a Masters
> in Aerospace Engineering and thought it was not.

I am not an Aerospace Engineer and do not play one on TV, so I just grabbed
"Theoretical Aerodynamics" by L. M. Milne-Thomson off my book shelf and
found the definition of "gliding angle" in section 1.02 (further discussion
in section 18.3). It appears that for lift L of the whole plane and drag D
of the whole plane then _by definition_ these are:

L = W*cos(gamma)
D = W*sin(gamma)

where gamma is the "gliding angle" (angle between the force vector A and
force vector V, where A is the aerodynamic force on the plane and V is the
velocity vector of the plane) and W the weight of the plane then it appears
that:

tan(gamma) = D/L

Perhaps Peter is confusing gliding angle with angle of incidence?
(According to the textbook definition of L, L need not remain at a fixed
angle (e.g. perpendicular) to the wing or any other line of the aircraft.
It is just the component of force, if any, perpendicular to V.)

On Mon, 04 Dec 2006 21:59:36 -0500, in
>, Peter Dohm wrote:
> I used to think that as well, but very reliable sources have told me
> that headaches and nausea are also frequently encountered--although not
> as commonly as sleepiness.

I've had headaches when I was at high altitudes for a prolonged period of
time while skiing... I had assumed that it was from caffeine withdrawal
though... Altitude sickness might have contributed a bit to it, but the
caffeine withdrawal headaches are strong enough that once you remove them,
you probably don't notice the one from altitude sickness... <grin>

T o d d P a t t i s t > wrote:
> I'm not sure what point you are trying to make. Peter is
> saying that varying weight changes the ratio between L
> (lift) and D (drag).

The point I'm making is that _by definition_ weight doesn't enter into
the computation of gliding angle. Odd, but that's because of the "un-
expected" way lift and drag are defined by aerodynamicists.

The question I then wondered was: from whence came Peter's idea that weight
was a factor?

You can actually read the relevant pages of the text I referenced by
going to Amazon.com and using their "Look Inside!" feature. Hopefully this
link should work:

http://www.amazon.com/gp/reader/048661980X/ref=sib_dp_pt/104-1851471-0992717#reader-link

The definition of gliding angle appears on page 2.

> The question I then wondered was: from whence came Peter's idea

whence came... "Whence" means "from where". "Whither" means "to where".

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.

Jose > wrote:
>> The question I then wondered was: from whence came Peter's idea
>
> whence came... "Whence" means "from where". "Whither" means "to
> where".

Thou tilts at windmills! My idiomatic use stands in good company:

http://www.worldwidewords.org/qa/qa-fro2.htm

Which states:

"And even a brief look at historical sources shows that from whence has
been common since the thirteenth century. It has been used by Shakespeare,
Defoe (in the opening of Robinson Crusoe: “He got a good estate by
merchandise, and leaving off his trade, lived afterwards at York; from
whence he had married my mother”), Smollett, Dickens (in A Christmas Carol:
“He began to think that the source and secret of this ghostly light might
be in the adjoining room, from whence, on further tracing it, it seemed to
shine”), Dryden, Gibbon, Twain (in Innocents Abroad: “He traveled all
around, till at last he came to the place from whence he started”), and
Trollope, and it appears 27 times in the King James Bible (including Psalm
121: “I will lift up mine eyes unto the hills, from whence cometh my
help”)."

So there! :-)

> >OK, I need to know how weight changes glide angle. I have a Masters in
> >Aerospace Engineering and thought it was not.
>
> There are two effects that I know of that come up in
> gliders. As you probably know, glider pilots care a lot
> about glide angles. :-) The first effect is structural.
> Carrying more weight can distort the shape of things.
> Racing gliders usually carry extra weight in the form of
> water ballast to increase the speed of best glide. That
> weight is carried in the wings in tanks located ahead of the
> spar. The extra weight distorts the shape of the airfoil
> (the nose of the wing sags a bit) and that can reduce glide
> angle somewhat.
>
> I know, that's not what you had in mind, but it's a real
> world effect.
>
> The other effect is even less, but more in the line I
> suspect you had in mind. When you fly faster, you change
> the Reynolds number. The airfoil operates slightly
> differently at slightly different Reynolds numbers, and that
> can change the glide angle a bit.
> --
Yes, remember that he did mention that the change was small. In addition to
reynolds number, and distortions of shape due to loading, there are also the
issues of intersection or interference drag and of Reynolds number--which
appears to have some effect even at very modest speeds.

I admit to knowing next to nothing about any of the above, and that I am not
at all sure that all work in the same direction, but I suspect that
increased weight will result in a slightly steeper glide angle in motionless
air in most cases.

Winds add additional variables, but I believe that Peter was correct.

(The other) Peter

> Thou tilts at windmills! My idiomatic use stands in good company...

Ok, let's examine them.

1: Shakespeare. Hmmph. The guy couldn't even spell his own name. How
can we put any credence in what he writes. Besides, I don't think any
of his plays survive in his own hand. Editors are notorious for being
creative with the English Language. So tosh on that!

2: Dickens. Pshaw. His contribution to English Literature centers
around grumpy people stomping on Christmas, and ghosts carrying people
through time machines to gawk at other people getting presents. Not
even worthy of consideration.

3: Mark Twain. How can I take anybody seriously if they go by a
pseudonym. Let's expose him as Samuel Langhorne Clemens, a jokester who
wrote about uneducated boys in the South. If he wrote about uneducated
boys, how can we believe that he was educated himself? He certainly
would not know how to use English properly. So there.

4: The King James Bible. Appealing to God for credibility, huh? First
of all, God flies without a pilot license; we certainly should not
condone anything else he does. Secondly, the Bible was not written in
English, it was written in Aramaic and other dead languages. They are
dead for a reason. Besides, I have sung parts of the bible in Oratorio
form (the only way it can be digested) and I most certainly have never
sung "from whence". That would have driven me deep into a mental
hospital, whence I might never have emerged. Here is the entire Soprano
I line from movement 28 of Mendelssohn's Elijah:

"Lift thine eyes, O lift thine eyes to the mountains, whence cometh,
whence cometh, whence cometh help. Thy help cometh from the Lord, the
Maker of heaven and earth. He hat hsaid, they foot shall not be moved.
Thy Keeper will never slumber, never, will never slumber, never
slumber. Lift thine eyes, O lift thine eyes, to the mountains, whence
cometh, whence cometh, whence cometh help, whence cometh, whence cometh,
whence cometh help."

There's not a "from" in the whole passage.

Now Elijah is probably the greatest Oratorio ever written, and
Mendelssohn one of the greatest musical composers that ever lived.

Whence. From where.

Take that, windmill! :)

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.

"Danny Dot" > wrote in message
...
>
> "Chris" > wrote in message
> ...
> snip
>
>>
>> Upto 10,000 ft air only
>> 10,000 - 33,700 ft Oxygen/air mix
>> 33,700 - 40,000 ft 100% oxygen
>> 40,000 + 100% Oxygen under pressure
>>
>>
>
> I flew fighters for the Air Force (F-4E) and I recal going to pressure
> breathing at about 25,000 feet cabin altitude. This was an emergency only
> because the cabin pressure never got this high. I also recall a rule to
> not go over 50,000 feet because of blood boiling (bends) IF the cabin
> pressure was lost at greater than 50,000 feet.

Well the bends more commonly known as Decompression Sickness (DCS) is a
possibility from about 18,000 ft unpressurised and is caused by the nitrogen
in the blood coming out.

The received wisdom is that if you have been scuba diving and gone deeper
than 30 ft (ie breath under pressure) then flying should be avoided for 24
hours.

whilst we are on it, the 8 hour bottle to throttle rule is a bit of a
fallacy too. It depend of course on how much was drunk. The body only breaks
down about 15mg of alcohol an hour and if one has been eating heavy meal in
an attempt to hold back the alcohol then it can only put back the clock from
when the body starts the breakdown process. A big meal only slows down the
absorption of alcohol by the body, it has no effect on the breakdown.

I suspect that those pilots who have been busted recently either don't know
or don't care to know how alcohol works in the body.

Personally its no booze for me 24 hours before flying.

On Tue, 05 Dec 2006 23:52:06 +0000, in
>, Chris wrote:
> Personally its no booze for me 24 hours before flying.

Damn, if that was the case, I would *never* get a chance to fly...
Personally, I have no problem with flying after having a full night's
sleep after having been drinking... But then again, I'm not trying to fly
first thing in the morning either... Hell, it takes a couple of hours just
to get my caffeine level up enough to just make the *drive* to the
airport... <grin>

> >
> >>
> >> Upto 10,000 ft air only
> >> 10,000 - 33,700 ft Oxygen/air mix
> >> 33,700 - 40,000 ft 100% oxygen
> >> 40,000 + 100% Oxygen under pressure
> >>
> >>
> >
> > I flew fighters for the Air Force (F-4E) and I recal going to pressure
> > breathing at about 25,000 feet cabin altitude. This was an emergency
only
> > because the cabin pressure never got this high. I also recall a rule to
> > not go over 50,000 feet because of blood boiling (bends) IF the cabin
> > pressure was lost at greater than 50,000 feet.
>
> Well the bends more commonly known as Decompression Sickness (DCS) is a
> possibility from about 18,000 ft unpressurised and is caused by the
nitrogen
> in the blood coming out.
>
> -----remainder snipped for brevity----------

I recall reading that the Blackbird crews (SR71 and U2) breathed pure oxygen
for several hours prior to each mission in order to clear their bodies of
dissolved nitrogen. I presume that the above was the reason.

Peter

Jose > wrote:
>> Thou tilts at windmills! My idiomatic use stands in good company...
>
> Ok, let's examine them.

[ Elided very amusing response for brevity. ]

> Whence. From where.
>
> Take that, windmill! :)

Ahem... Alonso Quixano eventually repented his madness on his deathbed. ;-)

> Ahem... Alonso Quixano eventually repented his madness on his deathbed. ;-)

.... and I thought you'd point out my one error. :) Oh well, this is
usenet. Make a mistake and nobody notices!

Besides, when he repented, he certainly didn't say "from whence my
madness cometh".

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.

Jose > wrote:
>> Ahem... Alonso Quixano eventually repented his madness on his
>> deathbed. ;-)
>
> ... and I thought you'd point out my one error. :) Oh well, this is
> usenet. Make a mistake and nobody notices!

Neglecting spelling and typos, and now that you've alerted me to an error,
the only two I've so far found are:

1) You said "There's not a "from" in the whole passage," yet one sticks out
like a sore "from whence":

"...cometh from the..."

2) Insulting Samuel Langhorne Clemens, one of my favorite authors. (I grew
up reading Robert Heinlein, among other SF authors, and later in life read
several of Clemens' works. Those Missouri boys sure knew how to write some
tall tales! Heinlein once wrote that he hadn't invented any new stories,
just filed off the serial numbers of some old ones and repackaged them.
After I read enough Twain, I realized from whence some of Heinlein's plots
came. ;-) )

> Besides, when he repented, he certainly didn't say "from whence my
> madness cometh".

Out of curiosity I did a text search of Project Gutenberg's online copy of
John Ormsby's famous translation of Don Quixote[1] and while Ormsby used
whence 29 times, he slipped up once and wrote "from whence" one of those
times.

[1] http://www.gutenberg.org/etext/996

> 1) You said "There's not a "from" in the whole passage,

Yep. That was it. I posted before checking. I repent. You can use
"from" and "whence" together, as long as you put a whole lot of words
between them. :)

> 2) Insulting Samuel Langhorne Clemens

Well, that's not an error, I think he would have approved. I like his
writing too; he really made things real. Heinlein's ok. I was about to
say unreadable, but I mistook him for Bradbury, who =is= unreadable.
Six times I tried to read "I sing the body electric" because the title
was so intriguing... six times I couldn't get past page thirty.

Back on topic, perhaps a body electric would be able to power an O2
concentrator, allowing unpressurized flight on Mars.

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.

Jose > wrote:
> Well, that's not an error, I think he would have approved. I like his
> writing too; he really made things real. Heinlein's ok. I was about to
> say unreadable, but I mistook him for Bradbury, who =is= unreadable.
> Six times I tried to read "I sing the body electric" because the title
> was so intriguing... six times I couldn't get past page thirty.

Bradbury's work is a mixed bag. I enjoyed The Martian Chronicles.

> Back on topic, perhaps a body electric would be able to power an O2
> concentrator, allowing unpressurized flight on Mars.

That would take a lot of body electricity! It would make more sense to
crack the CO2 in the Martian atmosphere into C and O2 than concentrate the
free O2:

http://en.wikipedia.org/wiki/Atmosphere_of_Mars

> That would take a lot of body electricity! It would make more sense to
> crack the CO2...

Yeah, I guess if you are on Mars, you do need to deal with Mars'
atmosphere, and not Earth's.

Bloody facts! :)

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.

"Peter Dohm" > wrote in message
...
>> >
>> >>
>> >> Upto 10,000 ft air only
>> >> 10,000 - 33,700 ft Oxygen/air mix
>> >> 33,700 - 40,000 ft 100% oxygen
>> >> 40,000 + 100% Oxygen under pressure
>> >>
>> >>
>> >
>> > I flew fighters for the Air Force (F-4E) and I recal going to pressure
>> > breathing at about 25,000 feet cabin altitude. This was an emergency
> only
>> > because the cabin pressure never got this high. I also recall a rule
>> > to
>> > not go over 50,000 feet because of blood boiling (bends) IF the cabin
>> > pressure was lost at greater than 50,000 feet.
>>
>> Well the bends more commonly known as Decompression Sickness (DCS) is a
>> possibility from about 18,000 ft unpressurised and is caused by the
> nitrogen
>> in the blood coming out.
>>
>> -----remainder snipped for brevity----------
>
> I recall reading that the Blackbird crews (SR71 and U2) breathed pure
> oxygen
> for several hours prior to each mission in order to clear their bodies of
> dissolved nitrogen. I presume that the above was the reason.
>
> Peter

Yep, goes back to Henry's Law , the gas dissolved in a liquid is
proportional to its pressure and brings us nicely back to the topic of
this thread.

Chris wrote:

>
> The received wisdom is that if you have been scuba diving and gone deeper
> than 30 ft (ie breath under pressure) then flying should be avoided for 24
> hours.

That's not a reasonable rule. The generally accepted rules run 18-24
hours, but they all START a with a single dive. Nitrogen absorption
is not just a matter of depth but also time. Even at 10 feet if you
dived for a for over an hour you'd be in trouble.


>
> I suspect that those pilots who have been busted recently either don't know
> or don't care to know how alcohol works in the body.
>
Busted, I don't know..but found to have alcohol after a crash, yes.
The first story in the "I Called It Pilot Error" book deals with
precisely this subjec.t

Chris writes:

> I suspect that those pilots who have been busted recently either don't know
> or don't care to know how alcohol works in the body.

People who fly aircraft should not be drinking alcohol or smoking at
all.

--
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On Tue, 05 Dec 2006 17:45:48 GMT, "Danny Dot" >
wrote in >:

>
>"Chris" > wrote in message
...
>snip
>
>>
>> Upto 10,000 ft air only
>> 10,000 - 33,700 ft Oxygen/air mix
>> 33,700 - 40,000 ft 100% oxygen
>> 40,000 + 100% Oxygen under pressure
>>
>>
>
>I flew fighters for the Air Force (F-4E) and I recal going to pressure
>breathing at about 25,000 feet cabin altitude. This was an emergency only
>because the cabin pressure never got this high. I also recall a rule to not
>go over 50,000 feet because of blood boiling (bends) IF the cabin pressure
>was lost at greater than 50,000 feet.
>
>
>Danny Dot
>>

Here's a little story on that topic:


A Frightening Parachute Ride

by Jim Bates

The U.S. Air Force song says, in part, "Off we go, into the wild
blue yonder,..."

Despite that "wild" warning in the beginning of a spirited
exaltation to the joys of flight, confident pilots often become
forgetful that it might be nice weather when a flight starts but it's
quite possible for aviators to experience first-hand how wild that
blue yonder can easily and quickly become.

Here's the tale-of a naval pilot who discovered the extent of
that wildness.

In May 1960, while flying in formation with another pilot, our
discoverer bailed out of a powerless F8U at 47,000 feet while on a VFR
(visual flight rules) journey from Massachusetts to North Carolina.
His unanticipated problems started while the two planes were passing
over a thunderstorm and his plane's engine made odd noises and a fire
warning light came on.

He took hurried corrective actions, but nothing worked. Abruptly
he was without power controls and the stick was locked in neutral
position. He hastily decided to eject rather than stay with the plane
that had started an uncontrollable plunge toward the raging storm
below.

Later reports estimated the thunderstorm to be some hundred miles
in diameter. His indicated airspeed at ejection was 210 knots (241.5
miles per hour).

The "wild blue yonder" gave him a frightening experience of a
nine-mile descent, lasting more than thirty minutes - an ordeal that
he fortunately survived - during which his parachute equipment did not
fail, though it had been subjected to extraordinary stresses. Parts of
his incredible adventure are given here in his words, garnered from
statements in an official U.S. Navy investigation.


* * *

"My first sensation was one of severe cold and extreme expansion,
as if I were about to explode. The cold rapidly changed to a burning,
tingling sensation. I felt as if millions of pins were sticking in me.
I sensed that I was tumbling and spinning like a cartwheel. My arms
and legs were out and I could not get them in.

"In a matter of seconds I realized I had retained my helmet and
mask but no longer had my visor although I had been flying with it
down because of the bright sunlight and reflection from the top of the
clouds. I believe it was torn away on ejection.

"I opened my eyes and saw I was entering wispy clouds. I was
going into the tops of the fleecy overcast that I had flown through
just a few minutes before. I seem to remember saying to myself, 'Well,
you're entering it and it's about 44,000 feet.' About this time I
managed to get my arms into my body.

"I looked down and noticed that I was absolutely forcing my torso
harness. It looked like it was going to burst. My stomach popped out
under my life vest as though I were pregnant.

"I had the feeling that I fell and fell and fell and fell for an
eternity. My oxygen mask was beating against my face. I held my mask
with my right hand. I put my left hand on my helmet which was pulling
on the chin strap as if it was going to go off. My left hand was very
cold and numb - it felt like somebody else's hand, not mine.

"Some time during the free fall, my right glove got in my way. It
inflated like a balloon so I let it go - just jettisoned it. I
remember seeing it go off and I thought 'Why did I throw the glove
away?'

"During the free fall I had the feeling of not being able to
exhale; in fact, I seemed to have to work very hard to be able to
exhale, but all I had to do was open my mouth and in-rushing air just
seemed to fill my lungs. At this time it was getting a bit darker in
the cloud.

"I had an urge to open the parachute but I told myself I was
still far too high and if I did I would either freeze to death or die
from lack of oxygen. I still had this tingling sensation but I sort of
had the feeling that I was slowing down and falling into denser
atmosphere and I seemed to be getting a little warmer.

"I was still in the free fall and thinking about opening the
chute. It was quite dark but I don't recall any great moisture or any
great violence. It seems like while I was thinking about opening the
chute, all of a sudden there was a terrific jolt and I knew the chute
had opened. I looked up but by this time I was in such a dense, dark
cloud that I couldn't even see my canopy. I reached up and got hold of
the risers and gave them tugs on both sides; it felt like I had a good
chute.

"From here on, my memory of what happened seems much better. I
now clearly recall running out of oxygen, having the mask collapse
against my face, and I believe I disconnected it from the right side
as I always do. At about this time I thought I definitely had it made
and was going to survive. However, I noticed I was still bleeding from
the nose, my right hand was cut, and my left hand was frozen numb, but
the pressure was going and I was much more comfortable. Then the
turbulence started and I realized I was entering the thunderstorm.

"As the turbulence started, I was pelted all over by hail. Then I
fell a little bit more and I seemed to be caught in a violent updraft.
I had the feeling that I was being tossed around - that I was actually
going around in a loop and I was looping over my canopy like being on
the end of a centrifuge. I got sick in the turbulence and heaved.

"Sometimes I could see the canopy and sometimes I couldn't. The
tossing and the turbulence was so violent it is difficult to describe.
I went up and down - I was buffeted about in all directions - at times
it felt like I was going sideways. One time I hit a very rough blast
of air - I went soaring back up and got in a very severe hailstorm. I
remember the hail beating down on my helmet. I had the feeling it
would tear my canopy up. The next thing I knew I was in rain so heavy
I felt like I was standing under a waterfall. I had my mask loose and
the water was so great that when I tried to inhale I got water with
the air like I was swimming. It seems to me that some time in the
storm I noticed my watch and was surprised that it had stayed with me.
I'm not sure but I think I was able to tell the time by the luminous
dial - I believe it was around 1815.

"At one time during an up or down draft, the parachute canopy
collapsed and came down over me like a big sheet. I could see my legs
in the shroud lines. This gave me some concern - I thought maybe the
chute wouldn't blossom again properly and since the hail seemed to be
larger now I was afraid it might damage the canopy and put holes in
it. I fell and the canopy blossomed again. I felt the risers and
everything seemed all right.

"At this time I looked down and saw what appeared to be a big
black elevator shaft. Then I felt like I had been hit by a blast of
compressed air and I went soaring back up again - up and down -
sideways. How much of this soaring went on I don't know. I had the
feeling that if it went on much longer I was not going to maintain
consciousness. I was being tossed around and beaten around and I
wasn't quite sure how much more I could take.

"The violence was so great that I thought that if it doesn't stop
soon, my gear will come apart - and my straps will break - I will come
apart. Stretching - twisting - slamming - the turbulence of this
thunderstorm was so violent I have nothing to compare it with. I
became quite airsick and I had considerable vertigo. Again I had the
feeling that I couldn't take much more of this but if I could only
hold out a little while longer, I would be falling out of the roughest
part of the storm.

"The lightning was so severe that I kept my eyes closed most of
the time. Even with my eyelids closed, there was a blinding
reddish-white light when the lightning flashed. I felt rather than
heard the thunder; it just about burst my eardrums. As I recall,
I had the feeling that I was in the upper part of the storm because
the lightning seemed to be just flashes. As I descended, I seemed to
see big red streaks heading towards the earth. All of a sudden I
realized it was getting a little calmer and I was probably descending
below the storm. The turbulence grew less, then ceased and I realized
I was below the storm. The rain continued, the air was smooth, and I
started thinking about my landing.

"By now my shoulders and legs hurt pretty badly. I checked myself
over again and thought I was O.K. I kept looking down and said to
myself 'Under the storm you probably won't have more than three
hundred feet.' It was just like breaking out when you're making a GCA
[ground controlled approach]. The first thing I saw was green and then
I was able to see trees and then I knew I was very close to the deck.

"I remember seeing a field off in the distance and I thought
there must be people nearby. As I got close to the trees I suddenly
realized there was a surface wind and I was being carried horizontally
over the ground quite rapidly - maybe 25 knots. I oscillated about
three times, then went into the trees. It seemed that my chute fouled
in two pine trees and I continued in a horizontal position with the
wind, then swung back to the left. I came crashing back through the
trees like a pendulum and hit a large tree with my left side. My head,
face, and shoulder took most of the blow. My helmet was knocked
crooked but I think it did a great deal to save me here. The blow was
so violent that it twisted my helmet back on the right side and pulled
the chin strap so tight over my Adam's apple under my chin that I had
to loosen it when I got on the ground. Anyway, I came down with a
crash. I slid down and landed on my side. I was cold and stunned but
still conscious. At first I thought I had broken something and was
paralyzed. Pretty soon, however, I was able to move my head and then
my arms. I checked the time; it was between 1840 and 1845."

The pilot's report went on to detail that he wasn't yet out of
trouble. It was still daylight but dimming quickly, and raining
heavily. The physically battered and stunned pilot struggled out
of the tangle of canopy, suspension lines, and harness webbing. He
wanted desperately to get out of the woods before dark, but he was
confused about what direction to go. Momentary panic worsened the
confusion but he forced himself to think rationally.

He then quickly recalled training in making square search
patterns. In the rainy darkness he saw a freshly cut tree stump, then
another, and another, then several more. He figured that a logging
operation of this size meant there would a logging road also. That
road would be the objective of his square search pattern.

On the third leg of the square pattern he found the road. In the
increasing darkness and steady rain he followed the dirt road until he
came to a farm field and across the field he saw automobile headlights
of several cars moving along a road. He wearily plodded through the
muddy field until he reached a paved two-lane secondary road.
Bedraggled, he stood on the edge of the road and tried to flag down a
passing car. He got annoyed, then angry, that by his count fifteen
cars went by without stopping to help.

His statement went on to read: "I must have looked like something
real unusual - all wet and bleeding and standing out there in my
flight suit in the dark and the rain. I guess they figured I was
drunk.

But suddenly he got a break: "Then after all these other cars had
kept on going, a car came by and I thought I heard a boy say, 'There's
a pilot, daddy."'

The car kept going into the rainy darkness, but then slowed,
turned around, and came back to the exhausted, hurt roadside figure.
The aviator's ordeal was done. He recovered from his injuries flew
again for many years.

The U.S. Navy's Approach magazine, produced for naval and marine
corps flight crew members, included the pilot's amazing flight
experience in an issue published soon after the official investigation
had been completed.

The "wild blue yonder" had been bested and another flyer's life
was saved with a parachute.


The author can be contacted via e-mail:
Copyright (c) 1995 Aero.com. All rights reserved.
http://aero.com/publications/parachutes/9610/pc1096.htm

LtCol. William H. Rankin
The Man Who Rode The Thunder


> Here's the tale-of a naval pilot who discovered the extent of
> that wildness.
>
> In May 1960, while flying in formation with another pilot, our
> discoverer bailed out of a powerless F8U at 47,000 feet while on a VFR
> (visual flight rules) journey from Massachusetts to North Carolina.
> His unanticipated problems started while the two planes were passing
> over a thunderstorm and his plane's engine made odd noises and a fire
> warning light came on.

The name of the pilot is William H. Rankin. At time Lt. Col. Rankin was
commanding officer of the Marine Corps Squadron VMF-122. He wrote a book,
The Man Who Rode the Thunder, about the event. I can't find my copy at the
moment.
I met Col. Rankin during one of my USMC tours after his experience. As I
recall, he ejected somewhere over Virginia and landed in North Carolina
almost an hour later. That he went on to fly again is testimony of what a
Marine Corp aviator is made of.
Sempre Fi!

On Wed, 06 Dec 2006 08:58:43 -0500, in
>, Ron Natalie wrote:
> That's not a reasonable rule. The generally accepted rules run 18-24
> hours, but they all START a with a single dive. Nitrogen absorption
> is not just a matter of depth but also time. Even at 10 feet if you
> dived for a for over an hour you'd be in trouble.

If I'm flying my plane after a dive, I just don't go that high... I'll
usually make the return flight at 1000 ft -- perhaps up to 3000 ft
sometimes...

AIM 8-1-2
http://www.faa.gov/ATpubs/AIM/Chap8/aim0801.html#8-1-2
Decompression Sickness After Scuba Diving.
1. A pilot or passenger who intends to fly after scuba
diving should allow the body sufficient time to rid itself
of excess nitrogen absorbed during diving. If not,
decompression sickness due to evolved gas can occur during
exposure to low altitude and create a serious in-flight
emergency.

2. The recommended waiting time before going to flight
altitudes of up to 8,000 feet is at least 12 hours after
diving which has not required controlled ascent
(nondecompression stop diving), and at least 24 hours after
diving which has required controlled ascent (decompression
stop diving). The waiting time before going to flight
altitudes above 8,000 feet should be at least 24 hours after
any SCUBA dive. These recommended altitudes are actual
flight altitudes above mean sea level (AMSL) and not
pressurized cabin altitudes. This takes into consideration
the risk of decompression of the aircraft during flight



The added pressure from a dive to 10 feet is 5 psi, at 30
feet the added pressure is 15 psi, making a total pressure
of 30 psi. That is double the sea level pressure so twice
the normal, amount of nitrogen will become dissolved in the
blood and tissue. This takes some time in both directions.
Mere skin or snorkel diving does not cause problems. But
the term saturation dive should be understood.
Decompression tables get the diver back to the surface, they
may just consider a slow swim up from 60 feet [or deeper] or
they may require stopping at certain depths to allow
dissolved gases to exit the blood to the lungs.



But keep in mind the soda bottle, you can unscrew the cap
and it may not bubble or it may over flow with a lot of
froth. If you're flying and climb fast, maybe some
turbulence [shaking your "bottle"] or a cabin decompression
or fast climb in a high performance airplane can cause you
pain. A single dive to less than 30 feet and 1 hour will
probably be clear 2 to 3 hours. A long day of multiple
dives to 30-60 feet, will take longer because you become
saturated.







"Grumman-581" > wrote
in message
...
| On Wed, 06 Dec 2006 08:58:43 -0500, in
| >, Ron
Natalie wrote:
| > That's not a reasonable rule. The generally accepted
rules run 18-24
| > hours, but they all START a with a single dive.
Nitrogen absorption
| > is not just a matter of depth but also time. Even at 10
feet if you
| > dived for a for over an hour you'd be in trouble.
|
| If I'm flying my plane after a dive, I just don't go that
high... I'll
| usually make the return flight at 1000 ft -- perhaps up to
3000 ft
| sometimes...

This thread has a lot of confusion.
I will try to resolve/simplify the confusion...


Suppose you are breathing 1 liter per minute.
(I'm using a round number not the correct one.)

If you are breathing normal air you get .21 liters of O2 at ambient pressure and .79 liters of nitorgen at ambient pressure.

If the concentrator takes in 4.76 liters of air and removes all the nitrogen (out to an exhaust port)
this leaves 1 liter of O2 at ambient presssure, you then breathe this 1 liter per minute of concetrated O2.

The keys are that the concetrator uses more air that you would (4.75 vs 1 liter) and
it exhausts most of that as pure nitrogen.

Notice that the concept of the concetrator is the same reguardless of altitiude,
it is increasing the concntration of O2 at sealevel this is 99% O2 at 14.7 PSI,
at 18000 ft this is 99% O2 at 7.3 PSI.

Paul

Jim Macklin wrote:
> AIM 8-1-2
> http://www.faa.gov/ATpubs/AIM/Chap8/aim0801.html#8-1-2
> Decompression Sickness After Scuba Diving.

Scuba divers are well advised to pay attention to the
diving-oriented medical research and not the FAA.