RTO MP-062 / HFM-050 - FTP Directory Listing - Nato

KN1-12
Figure 4 The relationships between the concentration of oxygen in the inspired gas and the pressure-altitude within
the pressurised cabin [cabin altitude] required
i. to maintain an alveolar PO2 of 103 mm Hg i.e. equivalent to breathing air at ground level [GL Equiv],
ii. to produce an alveolar PO2 of 30 mm Hg on an instantaneous decompression from the cabin altitude indicated
on the X axis of the figure to the cabin altitude/absolute intrapulmonary pressure indicated by the broken
horizontal curves [final cabin altitudes of 30,000, 35,000, 37,500 and 40,000 feet and final intrapulmonary
absolute pressures of 141 mm Hg (40,000 feet curve) 125 and 110 mm Hg],
iii. to ensure, with a cabin pressure differential of 5 Lb in -2 , that an instantaneous decompression from the cabin
altitude indicated on the X axis, the alveolar PO2 immediately after the decompression will be 30 mm Hg
when
a. using a pressure breathing system which provides a breathing pressure of 30 mm Hg gauge at 50,000
feet [50,000 FT; 30 mm Hg]
and
b. using a pressure breathing system which provides a breathing pressure of 70 mm Hg gauge at 60,000
feet [60,000 FT; 70 mm Hg].