Volume 6, Issue 10 (November 2009)

    Verification of the ASTM G-124 Purge Equation

    (Received 20 November 2008; accepted 19 August 2009)

    Published Online: 2009

    CODEN: JAIOAD

      Format Pages Price  
    PDF Version 9 $25   ADD TO CART


    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 E.
    Student Researcher, Dept. of Mathematics, Vanderbilt Univ., Nashville, TN

    Davis, Samuel Eddie
    Materials Engineer, Materials Combustion Research Facility, Materials Test Branch, NASA George C. Marshall Space Flight Center, Huntsville, AL

    Herald, Stephen D.
    Test Group Lead Engineer, InfoPro Corporation, Materials Test Branch, Materials Combustion Research Facility, NASA George C. Marshall Space Flight Center, Huntsville, AL


    Stock #: JAI102240

    ISSN: 1546-962X

    DOI: 10.1520/JAI102240

    ASTM International is a member of CrossRef.

    Author
    Title Verification of the ASTM G-124 Purge Equation
    Symposium Twelfth International Symposium on Flammability and Sensitivity of Materials in Oxygen-Enriched Atmospheres, 2009-10-09
    Committee G04