NOTE: Purifier cartridge should be changed after discharge of every 1.6
cylinders of oxygen. (T.O. 19-1-2) If this is not observed the
oxygen will contain moisture and freezing in oxygen system will
occur at high altitude.
After the oxygen in the tanks has had time to cool down, pressure
should be in the neighborhood of 400 pounds.
The same procedure must be employed even if one or more of the
systems is already fully charged since there is no way of equalizing
pressure among the different manifolds. Do not attempt to use any system
in which the pressure is less than 50 to 75 pounds per square inch.
Under these conditions the oxygen flow is very weak. More dangerous is
the possibility of moisture getting into the oxygen line through the
main recharger valve. This will result in freezing in the line or one of
the regulators on the next trip to high altitude.