STP1522

    Determination of Time Required for Materials Exposed to Oxygen to Return to Reduced Flammability

    Published: Jan 2009


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    Abstract

    Increased material flammability due to exposure to high oxygen concentrations is a concern from both safety and operational perspectives. Localized high oxygen concentrations can occur when exiting a higher oxygen concentration environment due to material saturation as well as oxygen entrapment between barrier materials. Understanding of oxygen diffusion and its correlation to flammability risks can reduce the likelihood of fires while improving procedures as NASA moves to longer missions with increased extravehicular activities in both spacecraft and off-Earth habitats. This paper examines the time required for common spacecraft materials exposed to oxygen to return to reduced flammability after removal from the increased oxygen concentration environment. Specifically, NASA-STD-6001A maximum oxygen concentration testing and ASTM Standard F1927 diffusion testing were performed on Nomex® HT90-40, Tiburon® surgical drape, cotton, Extravehicular Mobility Unit (EMU) Liquid-Cooled Ventilation Garment, EMU Thermal Comfort Undergarment, EMU Mosite foam with spandex covering, Advanced Crew Escape Suit (ACES) outer cross-section, ACES Liquid-Cooled Garment, ACES O2 hose material, Minicel® polyethylene foam, Minicel® polyethylene foam with Nomex® covering, Pyrell polyurethane foam, and Zotek® F-30 foam.

    Keywords:

    flammability, nonmetals, permeation, diffusion, diffusion, maximum oxygen concentration (MOC), gaseous oxygen enrichment, textiles, Extravehicular Mobility Unit, crew escape suit


    Author Information:

    Harper, Susana
    Engineer, NASA Johnson Space Center White Sands Test Facility, Las Cruces, NM

    Hirsch, David
    Engineer, Jacobs Technology, Inc., NASA Johnson Space Center White Sands Test Facility, Las Cruces, NM

    Smith, Sarah
    Mechanical Engineer, NASA Johnson Space Center White Sands Test Facility, Las Cruces, NM


    Paper ID: STP48832S

    Committee/Subcommittee: G04.01

    DOI: 10.1520/STP48832S


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