SYMPOSIA PAPER Published: 30 July 2014
STP155620130070

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

Source

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.

Author Information

Hertz, Daniel, L.
Seals Eastern Inc., Red Bank, NJ, US
Hertz, Daniel, L.
Seals Eastern Inc., Red Bank, NJ, US
Cook, Harold
Seals Eastern Inc., Red Bank, NJ, US
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Details
Developed by Committee: D15
Pages: 1–22
DOI: 10.1520/STP155620130070
ISBN-EB: 978-0-8031-7583-9
ISBN-13: 978-0-8031-7542-6