STP1040: Ignition of PTFE-Lined Flexible Hoses by Rapid Pressurization with Oxygen

    Janoff, D
    senior scientist with Lockheed-ESCengineer with Lockheed-ESCaerospace engineer with NASAaerospace technology materials engineer with NASA, NASA White Sands Test Facility (WSTF)WSTFWSTFJohn F. Kennedy Space Center, Las Cruces, NMFL

    Bamford, LJ
    senior scientist with Lockheed-ESCengineer with Lockheed-ESCaerospace engineer with NASAaerospace technology materials engineer with NASA, NASA White Sands Test Facility (WSTF)WSTFWSTFJohn F. Kennedy Space Center, Las Cruces, NMFL

    Newton, BE
    senior scientist with Lockheed-ESCengineer with Lockheed-ESCaerospace engineer with NASAaerospace technology materials engineer with NASA, NASA White Sands Test Facility (WSTF)WSTFWSTFJohn F. Kennedy Space Center, Las Cruces, NMFL

    Bryan, CJ
    senior scientist with Lockheed-ESCengineer with Lockheed-ESCaerospace engineer with NASAaerospace technology materials engineer with NASA, NASA White Sands Test Facility (WSTF)WSTFWSTFJohn F. Kennedy Space Center, Las Cruces, NMFL

    Pages: 21    Published: Jan 1989


    Abstract

    There has been increasing concern in recent years about the ignition sensitivity of polytetrafluoroethylene (PTFE) lined flexible hoses used in oxygen service. Stainless steel braided flexible hoses lined with PTFE were tested in a high-volume pneumatic-impact system. The objective of the testing was to characterize the ignition mechanism by determining the effects on ignition of impact pressure, pressurization rate, and volume upstream and downstream of the flexible hose. Ignitions occurred at impact pressures well below the working pressure of the hoses, and at pressurization rates that can easily be obtained with manually operated valves. The hoses ignited at the downstream end and combustion propagated back toward the source of fresh oxygen. The addition of stainless steel hardline downstream from the hose prevented ignitions at all pressures and pressurization rates. Internal observations revealed evidence of shock ionization of the oxygen prior to ignition. Although adiabatic compression of the oxygen is the most likely source of thermal energy for ignition, shock ionization of the oxygen may play an important role in the ignition mechanism by decreasing the activation energy necessary to kindle the reaction.

    Keywords:

    Ignition, PTFE, high-pressure oxygen, adiabatic compression, shock ionization


    Paper ID: STP24934S

    Committee/Subcommittee: G04.01

    DOI: 10.1520/STP24934S


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