With the present system in the B-24, each man has approximately 9
hours oxygen supply at 30,000 feet with the Auto-Mix on. However, it
occasionally becomes necessary in emergencies to calculate the residual
oxygen supply. This can be done by the simple formula given on page 24:
5 (man hours) x no. of intact
cylinders x actual pressure/400
divided by no. of men using the system.
Application of this formula is much simpler in the B-24, since
usually only one, and at the most two, men are using a single system.