Why oxygen duration would increase w/altitude?

[Checks]

http://www.ce560xl.com/files/Oxygen_Chart.pdf

For a non-jet or Excel guy, can anyone explain why oxygen duration increases with altitude?

Thanks in advance,

Mr. Not to Smart

 

[Whine Lover]

If you had graduated from Embry-Riddle Aeronautical University you would know the answer to this, and many other, necessary and ephemeral questions.

I could give you the answer.....But, it will cost you: "One Mee-lion Dollars".

Or, 4 years of current ERAU tuition, whichever is less.



YKW ( AKA: "Dickhead" )

 

[Whine Lover]

Oh...And the other answer IS:

"Because the Chart says so."

Do not question Authority....You will be sadly disappointed. ( With the foolishness of the answers.)

YKMKR

 

[Mike man]

I it has to do with the diluter demand system.

As long as the mask in not selected to 100% and to use diluter demand function the O2 will last for a while. Diluter demand will supply 100% O2 above a cabin altitude of (I don't know the exact altitude) using the chart it looks like the low 30's then it will supply 99%, 98%, 97% and so on down to 0% (or close to 0%) by mixing ambient air with the O2 as the airplane descends to a MEA or 10,000'.

You can try using diluter demand next time you pop on the O2 mask and de-select 100% and you will get hardly, if any, O2...this is due to the fact that the cabin altitude is less than 8,000'.

 

[Colonel Savage]

The higher you go, the closer you are to passing out, so you breathe less.

 

[ImbracableCrunk]

That table is missing a note:

"Cockpit masks are assumed to be at the normal setting below 20,000 feet
cabin altitude with a respiratory rate of 10 liters per minute - body
temperature pressure saturated and at 100% setting at and above 25,000
feet."

Maybe the BTPS dealy has something to do with it.

 

[Full of LUV]

The higher you go, the closer you are to passing out, so you breathe less.

Close, but as you increase in altitude the pressure is much less, thereby, one "breath" of oxygen is actually quite a bit less (of actual O2) because the gas has significantly expanded beyond what it was at lower altitudes. Since your lungs can only hold so much volume, even though you breath, the actual gas content is much less, hence the lack of absorption (coupled with the lack of partial pressure) into the bloodstream and your eventual demise....... did that sound technical enough to be possible?

 

[Lear70]

Moved into proper forum: General Aviation Chat

Please post questions in proper forums. The Major Airlines section is not there to answer General Aviation knowledge questions.

Thanks.

/mod

 

[Clipperskip]

Close, but as you increase in altitude the pressure is much less, thereby, one "breath" of oxygen is actually quite a bit less (of actual O2) because the gas has significantly expanded beyond what it was at lower altitudes. Since your lungs can only hold so much volume, even though you breath, the actual gas content is much less, hence the lack of absorption (coupled with the lack of partial pressure) into the bloodstream and your eventual demise....... did that sound technical enough to be possible?

We have a winner! Has little to do with diluter demand and more to do with partial pressures.....If you are a scuba diver it is the same concept. The lower you go the more O2 you use. It takes more O2 molecules to fill your lungs to equalize the extra force applied from the outside water presssure. Less outside pressure (higher altitude) less O2 required to fill lungs.

 

[jumppilot]

I it has to do with the diluter demand system.

As long as the mask in not selected to 100% and to use diluter demand function the O2 will last for a while. Diluter demand will supply 100% O2 above a cabin altitude of (I don't know the exact altitude) using the chart it looks like the low 30's then it will supply 99%, 98%, 97% and so on down to 0% (or close to 0%) by mixing ambient air with the O2 as the airplane descends to a MEA or 10,000'.

You can try using diluter demand next time you pop on the O2 mask and de-select 100% and you will get hardly, if any, O2...this is due to the fact that the cabin altitude is less than 8,000'.

Incorrect.

The higher you go, the less molecules you will breathe, regardless if you are 100% or Diluted. It doesn't matter if the air is a mix of ambient/100% or 100%, the amount of molecules needed to fill your lungs will decrease as the pressure pushing back (ambient) decreases.

The only reason we breathe is not because we suck in air, but because we allow the atmosphere to push in molecules as our muscles create an air pocket in our body, in an attempt to equalize the inside of our body with the outside.

That's why as you go higher you need a pressure suit, since you could take a full breathe, effectively equalizing your lungs and the ambient air, yet not take in enough O2 molecules to stay alive. It's not so much to increase the pressure of the air going into the lungs than it is to create an artificial atmosphere around you to make that full breath productive.

Bottom line, if you are at 30,000 feet breathing 100% it will last longer than if you are at sea level.