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The use of superoxide mixtures as air-revitalization chemicals in hyperbaric, self-contained, closed-circuit breathing apparatusIn portable breathing apparatus applications at 1 atm, potassium superoxide (KO2) has exhibited low-utilization efficiency of the available oxygen (O2) and diminished carbon dioxide-(CO2) scrubbing capacity caused by the formation of a fused, hydrated-hydroxide/carbonate product coating on the superoxide granules. In earlier work, it was discovered that granules fabricated from an intimate mixture of KO2 and calcium superoxide, Ca(O2)2, did not exhibit formation of a fused product coating and the utilization efficiency with respect to both O2 release and CO2 absorption was superior to KO2 granules when both types of granules were reacted with humidified CO2 under identified conditions. In the work described here, single pellets of KO2, KO2/Ca(O2), mixtures and commercially available KO2 tables and granules were reacted with a flow of humidified CO2 in helium at 1- and 10-atm total pressure and at an initial temperature of 40 C. In the 1-atm flow tests, the reaction rates and utilization efficiency of the KO2/Ca(O2)2 pellets were markedly superior to the KO2 pellets, tablets, and granules when the samples were reacted under identical conditions. However, at 10 atm, the rates of O2 release and CO2 absorption, as well as the utilization efficiencies of all the superoxide samples, were one-third to one-eighth of the values observed at 1 atm. The decrease in reaction performance at 10 atm compared to that at 1 atm has been attributed principally to the lower bulk diffusivity of the CO2 and H2O reactants in helium at the higher pressure and secondarily to the moderation of the reaction temperature caused by the higher heat capacity of the 10-atm helium.
Document ID
19850023518
Acquisition Source
Legacy CDMS
Document Type
Technical Memorandum (TM)
Authors
Wood, P. C. (San Jose State Univ. Calif., United States)
Wydeven, T. (NASA Ames Research Center Moffett Field, CA, United States)
Date Acquired
September 5, 2013
Publication Date
May 1, 1985
Subject Category
Man/System Technology And Life Support
Report/Patent Number
REPT-85193
NASA-TM-86709
NAS 1.15:86709
Accession Number
85N31831
Funding Number(s)
CONTRACT_GRANT: N61131-83-MP-30015
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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