In principle the demand regulator is a diaphragm-operated flow valve
which is opened by the user's inspiration and closes automatically when
the suction ceases. This gives you as much oxygen as you ask for. All
you do is breathe. A short breath draws a short squirt of oxygen, while
deep, rapid breathing brings forth large shots in rapid succession.
The regulator can be set to conserve oxygen, or to give you 100%
oxygen, regardless of the altitude you are flying. This is governed by
the position of the "Auto-Mix" (AIR) lever.
AUTO-MIX (AIR) "ON" (or NORMAL OXYGEN) is the position for routine
use. This saves oxygen.
(1) Gives a mixture of air and oxygen:
10,000 feet -- approx. 30% oxygen
18,000 feet -- approx. 65% oxygen
26,000 feet -- approx. 85% oxygen
30,000 feet -- approx. 100% oxygen
Under the above conditions, so far as oxygen is concerned, you are
at ground level.
(2) Use oxygen from ground level on night missions to prevent night
blindness.
(3) Increased altitude increases oxygen supply AUTOMATICALLY.
(4) Percentage of oxygen delivered keeps you at ground level efficiency.
(5) Ships oxygen supply, charged to 450 pounds lasts 10 men from 7 to 9
hours. (20,000 to 30,000 feet).
AUTO-MIX (AIR) "OFF (or 100% oxygen) -- used when ordered by first
pilot, and on special occasions.
(1) Gives 100% oxygen, on demand, regardless of altitude.
(2) Used on special occasions:
(a) To casualties suffering from:
1. Loss of blood.
2. Shock.
3. Passing out from oxygen lack (revived).
(b) Regulator not giving enough oxygen in "ON" position (blue
finger nails-beginning to feel pleased with yourself).
(c) To avoid gas poisoning if you land in a gassed area without gas
masks.
(d) To flush nitrogen gas from body fluids when going above 30,000
feet, helping to prevent bends.
(3) Ship's oxygen supply, charged to 450 pounds, lasts 6 hours or less.
THE "EMERGENCY" VALVE IS DANGEROUS -- it should be used with extreme
caution. A whole system can be depleted of oxygen in an hour or less if
the "emergency" is opened only a quarter of a turn. Emergency "ON"
changes regulator into a constant flow system and wastes precious
oxygen. Use only to revive an unconscious crew member or to check line
to make sure it is clear. Always make sure that "Emergency" is TIGHTLY
TURNED OFF before ship leaves the ground.
NOTE:
Don't be confused by the difference in appearance of demand
regulators manufactured by various companies (see Fig. 9). THEY ALL
WORK THE SAME.