1. When you are flying unpressurized.
  2. If you fly above 35,000 feet.
  3. Following explosive decompression (Blown blister).
  4. In all emergencies above 10,000 feet (Your Pressure must be released so emergency exits can be used).

OXYGEN SYSTEM

GENERAL:

Your oxygen system is a low pressure demand system with 14 oxygen stations corresponding to the various crew positions. The system utilizes the same type of equipment described for the Heavy Bombers:

  1. A-14 Demand Mask (See Pg. 8-16).
  2. A-12 Demand Regulator (See Pg. 17-19).
  3. Pressure Indicator (Pg. 31).
  4. Flow Indicator (Pg. 31).
  5. Eighteen Type G-1 low pressure cylinders (Pg.37).

DISTRIBUTION:

In the earlier B-29's, the oxygen cylinders were located in the center wing section. At present, however, the cylinders are distributed through the aft-portion of the ship. Regardless of the location of cylinders, distribution is essentially the same. This distribution is highly efficient. The entire loss of the O₂ supply to several crew positions has been practically eliminated by the following principle.

  1. EACH OF THE FOURTEEN OXYGEN STATIONS IS SUPPLIED FROM TWO WIDELY SEPARATED DISTRIBUTION LINES DRAWING FROM AT LEAST TWO CYLINDERS EACH. LOSS OF ONE LINE OR ITS ASSOCIATED CYLINDERS STILL LEAVES EACH STATION WITH AN ALTERNATE SOURCE OF OXYGEN.
  2. The entire system is self-equalizing by use of cross feeds and automatic check valves. If part of the system is shot out, all functioning stations will have equal access to the remaining supply.

Brief study of the diagram of the oxygen supply to a typical B-29 station (Fig. 15) will demonstrate the safety factors of this dual source supply.

Exact location of every oxygen cylinder and supply line may be found in the late tech orders.