This guideline describes the preparation of metal pressure vessels and the procedure for charging them with refrigerant and with the materials to be tested. A procedure for heating the metal vessel and regulating the pressure is described. Post-test evaluations can be performed quantitatively and/or qualitatively by observing the metal vessel contents to gain information for determining the compatibility@ suitability@ or chemical stability of materials in the refrigerant environment. The technique described can be used to evaluate many different types of materials. The guideline does not describe the detailed preparation of the materials to be tested prior to placing them in the metal vessel. The materials to be tested can be aged over a broad range of temperatures and pressures that fall within the safety limits of the vessel. Detailed safety precautions are included. Properly performing this test requires careful attention to the detailed experimental technique and careful adherence to safety procedures. PURPOSE This guideline is intended to establish a test procedure using metal pressure vessels for the evaluation of materials used in refrigeration systems. The use of metal vessels allows for the testing of a variety of materials@ regulation of the pressure of the test@ use of a realistic sample size to oil efrigerant ratio@ and other analytical tests@ such as extraction.