ASTM D6514 Standard Test Method for High Temperature Universal Oxidation Test for Turbine Oils
4. Summary of Test Method
4.1 After determining the viscosity at 40°C and acid number of a sample, a test specimen is stressed at 155°C for 96 h. After cooling, the test specimen is vacuum filtered for the determination of the total insolubles formed during the test. Total insolubles are reported as low, medium, or high.
4.2 The viscosity and the acid number of the filtrate are determined and compared with the initial values to ascertain any increase in those values. Both the change in acid number and the increase in viscosity at 40°C are reported.
4.3 The glass cell in which the test specimen was stressed is rinsed with heptane and dried. Residual deposits are compared with ASTM Adjunct ADJD6514, and the results are reported.
5. Significance and Use
5.1 Degradation of fluid lubricants because of oxidation or thermal breakdown can result in fluid thickening or in the formation of acids or insoluble solids and render the fluid unfit for further use as a lubricant.
5.2 This test method can be used for estimating the oxidation stability of oils. It can function as a formulation screening tool, specification requirement, quality control measurement, or as a means of estimating remaining service life. It shall be recognized, however, that correlation between results of this test method and the oxidation stability of an oil in field service can vary markedly with field service conditions and with various oils.
5.3 This test method is designed to compliment Test Method D5846 and is intended for evaluation of fluids which do not degrade significantly within a reasonable period of time at 135°C.
