ASTM D5846 Universal Oxidation Test for Hydraulic and Turbine Oils
ASTM D5846 Standard Test Method for Universal Oxidation Test for Hydraulic and Turbine Oils Using the Universal Oxidation Test Apparatus
4. Summary of Test Method
4.1 An oil sample is contacted with air at 135°C in the presence of copper and iron metals. The acid number and spot forming tendency of the oil are measured daily. The test is terminated when the oxidation life of the oil has been reached.
4.2 The oil is considered to be degraded when either its acid number (measured by Test Methods D974 or D664) has increased by 0.5 mg KOH/g over that of new oil; or when the oil begins to form insoluble solids so that when a drop of oil is placed onto a filter paper it shows a clearly defined dark spot surrounded by a ring of clear oil.
5. Significance and Use
5.1 Degradation of hydraulic fluids and turbine oils, because of oxidation or thermal breakdown, can result in the formation of acids or insoluble solids and render the oil unfit for further use.
5.2 This test method can be used to estimate the relative oxidation stability of petroleum-base oils. It should be recognized that correlation between results of this test and the oxidation stability in use can vary markedly with service conditions and with various oils.
