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Verification of the ASTM G-124 Purge EquationASTM G-124 seeks to evaluate combustion characteristics of metals in high-purity (greater than 99%) oxygen atmospheres. ASTM G-124 provides the following equation to determine the minimum number of purges required to reach this level of purity in a test chamber: n = -4/log10(Pa/Ph), where "n" is the total number of purge cycles required, Ph is the absolute pressure used for the purge on each cycle and Pa is the atmospheric pressure or the vent pressure. The origin of this equation is not known and has been the source of frequent questions as to its accuracy and reliability. This paper shows the derivation of the G-124 purge equation, and experimentally explores the equation to determine if it accurately predicts the number of cycles required.
Document ID
20090042868
Acquisition Source
Marshall Space Flight Center
Document Type
Preprint (Draft being sent to journal)
Authors
Robbins, Katherine E. (Vanderbilt Univ. Nashville, TN, United States)
Davis, Samuel Eddie (NASA Marshall Space Flight Center Huntsville, AL, United States)
Date Acquired
August 24, 2013
Publication Date
October 7, 2009
Subject Category
Chemistry And Materials (General)
Report/Patent Number
M09-0198
Meeting Information
Meeting: Twelfth International Symposium on Flammability and Sensitivity of Materials in Oxygen Enriched Atmospheres
Location: Berlin
Country: Germany
Start Date: October 7, 2009
End Date: October 9, 2009
Sponsors: American Society for Testing and Materials
Distribution Limits
Public
Copyright
Public Use Permitted.

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