Destination Moon Site Index
Apollo 11 Hatch Gallery


Walk-around of the cabin purge port

Picture 3 of 3.

After the Apollo 1 fire, the atmosphere inside the command module was changed from 100% oxygen to a sea-level pressure mixture of 60% oxygen and 40% nitrogen, which reduced the fire hazard. The pressure and composition of the cabin gas during the prelaunch period was controlled by ground support equipment through the purge port. During launch, a pressure relief valve vented the excess gas overboard. During normal space operations, cabin atmosphere was pure oxygen and the pressure was maintained at 5 psi.

Cabin purge port on Apollo 11 Hatch at Destination Moon
Time picture taken Thu Aug 23 10:07:34 2018
Location picture taken Boeing Hall
St. Louis Science Center
St. Louis, MO
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