Modification of a Calorimetric Oxygen Detector for use with Non-Equilibrium Hydrogen
A calorimetric method1 has been used for trace oxygen analysis in the CEL-NBS hydrogen liquefier. In this method any oxygen present is catalytically combined with the hydrogen to form water. The resulting temperature rise of the gas is measured by a sensitive thermopile. The analyzer is capable of detecting as little as 2 ppm of oxygen. With the introduction of a catalyst to produce high para liquid hydrogen in the liquefier this system no longer operates with its former precision. The boil-off gas from the liquid hydrogen receiver and from a dewar being filled is recirculated through the system. The result is a non-equilibrium ortho-para mixture in the room temperature gas at the oxygen analyzer. The catalyst used to combine the oxygen and hydrogen effectively converts this high-para gas to normal equilibrium hydrogen. Since the conversion is an endothermic reaction, the analyzer reads too low and may even give negative readings.
KeywordsLiquid Hydrogen Oxygen Analyzer Commercial Model Negative Reading Cryogenic Engineer
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- 2.D. H. Weitzel and R. L. Hershey, Continuous Analysis of Orthoparahydrogen Mixtures, paper C-2 of the 1954 Cryogenic Engineering Conference Proceedings, Commercial model used is Gow-Mac Thermal Conductivity cell type recorder -4, improved standard geometry with MT-T filaments, Manufactured by the Gow-Mac Instrument Company, 100 Kings Road, Madison, New Jersey.Google Scholar