O2 Concentrator instead of O2 tank

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



"Vaughn Simon" wrote in message
...

"Chris W" wrote in message
news

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

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.

"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

"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
KE5GIX

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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

"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