Journal Published Online: 11 September 2009
Volume 6, Issue 10

Verification of the ASTM G-124 Purge Equation

CODEN: JAIOAD

Abstract

ASTM G-124 seeks to evaluate combustion characteristics of metals in high-purity (>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 provides the derivation of the G-124 purge equation, and experimentally explores the equation to determine if it accurately predicts the number of cycles required.

Author Information

Robbins, Katherine
Dept. of Mathematics, Vanderbilt Univ., Nashville, TN
Davis, Samuel
Materials Combustion Research Facility, Materials Test Branch, NASA George C. Marshall Space Flight Center, Huntsville, AL
Herald, Stephen
InfoPro Corporation, Materials Test Branch, Materials Combustion Research Facility, NASA George C. Marshall Space Flight Center, Huntsville, AL
Pages: 9
Price: $25.00
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Details
Stock #: JAI102240
ISSN: 1546-962X
DOI: 10.1520/JAI102240