ASTM D2112 for oxidation stability of inhibited mineral insulating oil
ASTM D2112 standard test method for oxidation stability of inhibited mineral insulating oil by pressure vessel
10. Interpretation of Results
10.1 Observe a plot of the recorded pressure versus time and establish the plateau pressure (see Note 7). Also record the time at the point on the falling part of the curve where the pressure is 25 psi (172 kPa) less than the established plateau pressure. Plateau pressures in duplicate tests should not differ by more than 5 psi (35 kPa).
10.2 The vessel life of the test specimen is the time in minutes from the start of the test to a 25-psi pressure drop from the level of the established plateau.
11. Report
11.1 Report the time as the average of two duplicate determinations and the difference of the individual determinations. The recipient of the report can then be reassured that the determination is not suspect, as specified in 12.1.
12. Precision and Bias
12.1 The following criteria should be used for judging the acceptability of results (95 % probability):
12.1.1 Repeatability - Duplicate determinations by the same operator should not be considered suspect unless they differ by more than 23 min. If the two results differ by more than the specified value, another set of duplicate tests should be performed.
12.1.2 Reproducibility - Results submitted by each of two laboratories based on the average of two determinations in each laboratory should not be considered suspect unless they differ by more than 43 min.
12.2 No justifiable statement can be made on the bias of the procedure in this test method since there is no accepted reference material suitable for determining oxidation stability.
13. Keywords
13.1 electrical; inhibitor; insulating oil; mineral oil; oxidation stability; pressure vessel; rotating vessel; transformer oil
