Investigation of the Occurrence of Condensation in Flight Instruments
Final technical rept. Sep 1963-Dec 1965
BATTELLE MEMORIAL INST COLUMBUS OH
Pagination or Media Count:
This study is related to the location and identification of sources of fog formation on the faceplates of hermetically sealed aeronautical instruments. Two types of fog moisture and permanent were found. Moisture fog was shown to be caused by imperfect hermetic sealing of the instrument cases. Permanent oily fog was found to be the result of partial decomposition of nonmetallic materials by heat. This decomposition in certain materials results in oily products with appreciable vapor pressure, which may condense on the instrument faceplate, usually the coolest part of the instrument. Thirteen aeronautical instruments representing seven different types, and made by five different suppliers, were covered by this study. Included in the report are 1 A list of recommended materials 2 a list of materials shown to contribute to permanent-fog formation 3 a discussion of the psychrometry of gases 4 a discussion of desiccants 5 a critique of the ice-cube test 6 a recommended modification of the ice-cube test to duplicate more nearly the use conditions 7 a description of a high-sensitivity fog-potential test 8 instructions for the use of the test in Item 7 and 9 pertinent excerpts from the International Critical Tables.
- Flight Control and Instrumentation
- Manufacturing and Industrial Engineering and Control of Production Systems