This classification system tabulates the properties of vulcanized rubber materials (natural rubber@ reclaimed rubber@ synthetic rubbers@ alone or in combination) that are intended for@ but not limited to@ use in rubber products for automotive applications. N0TE i_This document may serve many of the needs of other industries in much the same manner as SAE numbered steels. It must be remembered@ however@ that this system is subject to revision when required by automotive needs. It is recommended that the latest revision always be used. This document is based on the premise that all rubber materials intended for use in rubber products can be arranged into characteristic designations. These designations are determined by types@ based on resistance to heat aging@ and classes@ based on resistance to swelling by oil. Basic levels are thus established which@ together with values describing additional requirements@ permit complete description of the properties of all rubber materials. In all cases where provisions of this document would conflict with those of the detailed specifications for a particular product@ the latter shall take precedence. NOTE 2??When the rubber product is to be used for purposes where the requirements are too specific to be completely prescribed by this classification system@ it is necessary for the purchaser to consult the supplier in advance to establish the appropriate properties@ test methods@ and specification test limits. Purpose The purpose of this document is to provide guidance to the engineer in the selection of practical@ commercially available rubber materials@ and further to provide a method by which these materials may be specified by the use of a simple line call-out designation. This document was developed to permit the addition of descriptive values for future rubber materials without complete reorganization of the classification system and to facilitate the incorporation of future new methods of test to keep pace with changing industry requirements.