Designation:D395-03 INTERNATIONAL StandardTestMethodsfor Rubber Property-Compression Set1 This standard is issued under the fixed designation D 395; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (e) indicates an editorial change since the last revision or reapproval. This standard has been approved for use by agencies of the Department of Defense. 1. Scope E145 Specification for Gravity-Convection and Forced- Ventilation Ovens3 1.1 These test methods cover the testing of rubber intended foruse in applications inwhich therubberwill be subjected to 3. Summary of Test Methods compressive stresses in air or liquid media. They are applicable 3.1 A test specimen is compressed to either a deflection or particularly to the rubber used in machinery mountings, vibra- by a specified force and maintained under this condition for a tion dampers, and seals. Two test methods are covered as specified time and at a specified temperature. follows: 3.2 The residual deformation of a test specimen is measured Test Method Section 30 min after removal from a suitable compression device in ACompression Set Under Constant Force in Air 710 which the specimen had been subjected for a definite time to BCompression Set Under Constant Deflection in Air 1114 compressive deformation under specified conditions. 1.2 The choice of test method is optional, but consideration 3.3 After the measurement of the residual deformation, the should be given to the nature of the service for which compression set, as specified in the appropriate test method, is correlation of test results may be sought. Unless otherwise calculated according to Eq 1 and Eq 2. stated in a detailed specification, Test Method B shall be used. 4. Significance and Use 1.3 Test Method B is not suitable for vulcanizates harder than 90 IRHD. 4.1 Compression set tests are intended to measure the ability 1.4 The values stated in SI units are to be regarded as the of rubber compounds to retain elastic properties after pro- longed action of compressive stresses. The actual stressing standard. 1.5 This standard does not purport to address all of the service may involve the maintenance of a definite deflection, safety concerns,if any, associated with its use.It is the the constant application of a known force, or the rapidly responsibility of the user of this standard to establish appro- repeated deformation and recovery resulting from intermittent priate safety and health practices and determine the applica- compressive forces. Though the latter dynamic stressing, like bility of regulatory limitations prior to use. the others, produces compression set, its effects as a whole are simulated more closely by compression flexing or hysteresis 2.Referenced Documents tests. Therefore, compression set tests are considered to be 2.1 ASTM Standards: mainlyapplicabletoserviceconditionsinvolvingstatic D1349Practice for Rubber-Standard Temperatures for stresses. Tests are frequently conducted at elevated tempera- Testing? tures. D3182 Practice for Rubber—Materials,Equipment, and 5. Test Specimens Procedures for Mixing Standard Compounds and Prepar- ing Standard Vulcanized Sheets2 5.1 Specimens from each sample may be tested in duplicate D3183Practice for Rubber—Preparation of Pieces for Test (Option 1) or triplicate (Option 2). The compression set of the Purposes from Products2 sample in Option 1 shall be the average of the two specimens D3767PracticeforRubber-—Measurement of Dimensions2 expressed as a percentage. The compression set of the sample D 4483 Practice for Determining Precision for Test Meth- in Option 2 shall be the median (middle most value) of the three specimens expressed as a percentage. ods Standards intheRubber and Carbon Black Industries 5.2 The standard test specimen shall be a cylindrical disk cut from a laboratory