ASTM D972 Test Method forEvaporation Loss of Lubricating Greases and Oils
4. Summary of Test Method
4.1 The weighed sample of lubricant in an evaporation cell is placed in a bath maintained at the desired test temperature. Heated air is passed over its surface for 22 h. The evaporation loss is calculated from the loss in mass of the sample.
5. Significance and Use
5.1 The loss of volatile materials from greases and oils can adversely effect the original performance characteristics of a lubricant and therefore could be a significant factor in evaluating a lubricant for a specific use. Such volatiles can also be considered contaminants in the environment in which the lubricant is to be used. Correlation between results from this test method and service performance has not been established.
5.2 The test can be run at any agreed upon temperature between 100 and 150°C (210 to 300°F).
NOTE 1 - The specified flow of air, 2.58 +/-0.02 g/min, (2L/min at standard temperature and pressure), assumes dry air. It is not known that the original work involved dry air but it has since been shown that this can be a factor in reproducibility and should be addressed. A dew point of less than 10°C at standard temperature and pressure will be satisfactory.
NOTE 2 - To determine evaporation loss at temperatures above 150°C (300°F), see Test Methods D2595.
