Classifications System for Elastomeric Materials for Automotive Applications This specification system has been devised jointly by the ASTM Committee D 11 on rubber and rubberlike material and the Society of Automotive Engineers (SAE). It is of sufficient interest and importance to warrens its reproduction in part and to show how it may be used. The following may be considered an abbreviated course on how to interpret a typical "line call-out" or specification using the example outlined in the D 2000 publication. An example line call-out may comprise the following letters and numbers: 2BC 510A14E034 The first portion of the call-out is called the basic requirements. This consists of the 2BC 510. The basic requirements may be interpreted as follows:  2 = Grade number. This defines the performance level for she suffix requirements. B = The material type. This defines the aging temperature requirements. B type materials are aged at 100°C (212° F) C = The material class. This determines the oil swell requirements. C class materials have a 120% maximum volume swell in ASTM No. 3 Oil. 5 = The target hardness, 50 + 5 Shore A 10 = The minimum tensile strength, 1000 psi. If the line call-out starts with the letter M (for metric), the tensile is given in MPa (Since 1000 psi = 7 MPa, the equivalent metric call-out is M2BC 507.) The letters and numbers following the basic requirements are called the suffix requirements. These are added only as needed to meet specific end-use requirements. For example, the A14E034 suffix requirements may be interpreted as follows:  A = Special heat resistance, -15% maximum tensile change and -40% maximum elongation change. Without the A14 suffix, the basic type materials are permitted + 30% tensile change and -5% elongation change after heat aging. 1 = The test method for heat resistance, ASTM D 573 for 70 hours. 4 = The test temperature for heat resistance, 100°C (212°F). EO = Fluid resistance (oils end lubricants). As the case for heat resistance, this suffix allows less change in properties after ASTM No. 3 Oil immersion than the basic C class material. 3 = The test method for fluid resistance, ASTM D 471 in No. 3 Oil for 70 hours. 3 = The test temperature for heat resistance, 100° C (212° F).