Oxygen in cabins

[Olendirk]

Hey,

one more:-) : I know that we're regulating the pressure and the oxygenflow of a cabin. but where does the cabin get the oxygen for a flight for about 12 hours in 39000 feet?
how big are the reserves and tanks?

Thanks!

OD

we\'ll sorry for the stupid question, i got it myself. the quantity of oxygen remains the same in the atmosphere with 21%. now it depends on the partial pressure, and this partial pressure decreases with altitude and thats why why we pressurize the cabin, is that right?:ok:

[moo]

pretty much! :ok:
the air is bled off the engine compressor (before it enters the combustion chamber :} ) and is then cooled through precoolers and air conditioning packs before entering the cabin.
Oxygen is used directly from cylinders in emergency situations only.

[Mass Times Velocity]

... which means you could in theory stay up there until there's no fuel left and the engines stop (not a very good idea)!!!