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    STP1556

    The Effect of Long-Term Intermittent Service on Elastomers in Aqueous Engine Coolants

    Published: 2014


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    Abstract

    Synthetic rubber (elastomeric) o-ring seals are widely used in modern CI and SI power systems. They are increasingly challenged by higher thermal inputs, design considerations, and long-term warranty issues. This paper presents comprehensive, quantitative aging data for evaluating popular elastomers used for sealing coolants. Three categories of commercial heavy-duty (HD) engine coolants were used as test media. The commercially available elastomers tested in this study were: fluoroelastomers (FKM-type 2), tetrafluoroethylene–propylene rubber (FEPM), and hydrogenated nitrile rubber (HNBR). The study sought to duplicate the effects of multiple engine startups and shutdowns. The test protocol involved 100 twenty-four hour cycles consisting of 16 h operation at 150°C and an 8-h cool down. The test fixtures, run in triplicate, provide O-rings sealing axially (flange seal design), radially (piston seal design), and a straight thread port seal. The test fixtures subjected seals to saturated vapor on one side and liquid on the other. Data was developed and reported in accordance with ASTM D1414-94 and ASTM D412-06a. Compressive stress relaxation is reported in accordance with ASTM D6147. To monitor degradation of the fluoroelastomers, coolant was monitored for fluoride ion activity. A brief discussion on polymer stability in high pH aqueous and nonaqueous fluids is included.

    Keywords:

    coolant, high temperarure, elastomers


    Author Information:

    Hertz, Daniel L.
    Seals Eastern Inc., Red Bank, NJ

    Cook, Harold
    Seals Eastern Inc., Red Bank, NJ


    Committee/Subcommittee: D15.21

    DOI: 10.1520/STP155620130070