Daddy, what did you do in World War II? Drying oxygen for high-altitude flight.

 

 

 

 

 

 

 

 

 

 

 

 

 When I was in my early teens, my father Harold told me about an important project which he had been involved in during World War II. It had largely been kept secret, and was a detail not covered in most history books. Military aircraft flying at high altitudes needed to supply oxygen to aircrew via masks. But if the oxygen was not very dry, then ice would form and clog the regulator.

 

The Army Air Corps had determined that the oxygen should be dried to a dew point of -67 F. They asked several companies about producing a drying apparatus. General Air Conditioning (GAC) was the one they chose. The president, George Metzger, visited dad at the chemical engineering department of the University of Cincinnati, and hired him as a consultant to develop their drying system. Slightly moist gas from tall 2000 psi oxygen tanks was passed through a GAC-3 drying cartridge before it went into the 400 psi tanks on heavy bombers like the B-17 Flying Fortress and B-24 Liberator (shown above).

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The cartridges GAC produced for drying oxygen were cylinders with a shape similar to the cans used for three tennis balls, as shown above. 

 

 

 

 

 

 

 

 

 

 

 

 

 

They were filled with anhydrous calcium sulfate granules. There were felt disks and steel mesh screens at the ends (as also shown above) to prevent fine particles from getting into the gas stream. A cartridge could dry the oxygen for filling the tanks on sixteen heavy bombers. After he filled the tanks on a bomber, the ground crew member put a chalk tally mark on the outside of the drying apparatus. 3,625,000 of these cartridges were produced. Dad and another engineer tested a sample of one in 500 of them for quality control by using wet nitrogen gas fed through a frost-point hygrometer. 

 

There is no mention of these drying cartridges in the 1052-page book about Medical Support of the Army Air Forces in World War II or this YouTube video about the B-17 oxygen system.

 

Images of B-24 bombers and a can for tennis balls are from Wikimedia Commons.