Ignition Sensitivity of Nonmetallic Materials in Oxygen-Enriched Air (NITROX): A Never Ending Story in SCUBA Diving?

    Volume 6, Issue 8 (September 2009)

    ISSN: 1546-962X

    CODEN: JAIOAD

    Published Online: 14 July 2009

    Page Count: 7


    Binder, Chr.
    Specialist of Working Group “Safe Handling of Oxygen, Division II.1 “Gases, Gas Plants,” BAM Federal Institute for Materials Research and Testing, Berlin,

    Brock, T.
    Specialist of Working Group “Safe Handling of Oxygen, Division II.1 “Gases, Gas Plants,” BAM Federal Institute for Materials Research and Testing, Berlin,

    Hesse, O.
    Specialist of Working Group “Safe Handling of Oxygen, Division II.1 “Gases, Gas Plants,” BAM Federal Institute for Materials Research and Testing, Berlin,

    Lehné, S.
    Specialist of Working Group “Safe Handling of Oxygen, Division II.1 “Gases, Gas Plants,” BAM Federal Institute for Materials Research and Testing, Berlin,

    Tillack, T.
    Specialist of Working Group “Safe Handling of Oxygen, Division II.1 “Gases, Gas Plants,” BAM Federal Institute for Materials Research and Testing, Berlin,

    (Received 5 December 2008; accepted 12 June 2009)

    Abstract

    Self-contained underwater breathing apparatus (SCUBA) divers use different mixtures of nitrogen and oxygen as breathing gas. The so-called NITROX mixture often contains more oxygen than is contained in air and may increase the fire hazard in diving equipment. The SCUBA diving community, however, still differentiates between NITROX mixtures that contain more than 40 % oxygen or less. They consider a mixture with up to 40 % oxygen often as regular air. In filling operations of SCUBA cylinders, gas flows from high pressure to low pressure. Because of compressive heating, a sudden temperature rise in the gas occurs and nonmetallic materials, e.g., seals may ignite. BAM has used the pneumatic impact test to investigate the ignition sensitivity of ethylene propylene diene monomer (EPDM), fluorelastomer (FPM), polytetrafluorethylene (PTFE), polyetheretherketone (PEEK), and nylon (PA 6.6) to gaseous impacts in synthetic air, in various NITROX mixtures, and in pure oxygen. The test results clearly show that for nonmetallic materials, the maximum pressure of nonreaction in NITROX mixtures decreases at a content of 29 % oxygen in comparison to those in air. In addition, autoignition temperatures of the nonmetallic materials were also determined. The findings of this investigation support very well the results of other publications on oxygen enrichment. As a consequence of this study, in SCUBA diving, the same safety requirements for NITROX mixtures with more than 21 % oxygen should be applied as for pure oxygen in the industry.


    Paper ID: JAI102262

    DOI: 10.1520/JAI102262

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    Author
    Title Ignition Sensitivity of Nonmetallic Materials in Oxygen-Enriched Air (NITROX): A Never Ending Story in SCUBA Diving?
    Symposium Twelfth International Symposium on Flammability and Sensitivity of Materials in Oxygen-Enriched Atmospheres, 2009-10-09
    Committee G04