The Effects Of Contaminated Engine Coolants On The Service Life Of Elastomers 2001-01-1180

Service life of elastomers is usually evaluated in the environment in which the elastomer is required to perform. Generally, the environment is considered to be a single fluid. However, inquiries from heavy duty and automotive OEMs regarding the cross contamination of fluids in coolant systems, has been steadily increasing. Additionally, numerous articles and technical bulletins have been written regarding the cross contamination of fluids. Various elastomers can be used in coolant systems; however, studies in the past have shown that the elastomers that are best for coolant systems may not be suitable once contaminants are introduced.

With the introduction of Organic Acid Technology (OAT) coolants and Hybrid (Conventional/ OAT technology) into the automobile and truck markets, it has become necessary to perform elastomer compatibility studies to insure that seal materials will withstand the new fluids. This paper will compare Silicone (VMQ), Ethylene Propylene Terpolymer (EPDM), Hydrogenated Nitrile Rubber (HNBR), and Fluoroelastomer (FKM) rubber compound formulations in a conventional coolant and a Hybrid (European) coolant, diluted with engine lube oil 5%, to show the effects of oil contamination on the elastomers. Standard bench tests were used to conduct the evaluations. High temperature, (150°C) and low temperature (100°C) was used to measure the effects of high temperature accelerated aging on the elastomers as well as the coolants. Additionally, this range should cover all potential operating temperatures.