ASTM D942 standard test method for oxidation stability of lubricating greases by the oxygen pressure vessel method
9. Report
9.1 Report the average of duplicate determinations as pressure drop in pounds per square inch, or kilopascals for the specified test time, or times in hours, according to Test Method D942.
10. Precision and Bias
10.1 The precision of this test method as determined by statistical examination of interlaboratory results is as follows:
10.1.1 Repeatability - The difference between two test results, obtained by the same operator with the same apparatus under constant operating conditions on identical test material would, in the long run, in the normal and correct operation of the test method, exceed the following values only in one case in twenty:
10.1.2 Reproducibility - The difference between two single and independent results obtained by different operators working in different laboratories on identical test material would, in the long run, in the normal and correct operation of the test method, exceed the following values only in one case in twenty:
NOTE 6 - These precision values apply only to that portion of the data for which oxygen is absorbed at a rate approximately proportional to time (for example, the induction period). The end of the induction period is evidenced by a rapid acceleration in the rate of oxygen absorption in a short time interval.
10.2 The following information on the precision of this test method has been developed by the Institute of Petroleum (London). The precision of this test method as determined by statistical examination of interlaboratory results is as follows:
10.2.1 Repeatability - The difference between two test results, obtained by the same operator with the same apparatus under constant operating conditions on identical test material would, in the long run, in the normal and correct operation of the test method, exceed the following values only in one case in twenty:
10.2.2 Reproducibility - The difference between two single and independent results obtained by different operators working in different laboratories on identical test material would, in the long run, in the normal and correct operation of the test method, exceed the following values only in one case in twenty:
These precision values have been obtained by statistical examination of interlaboratory test results, and were first published in 1965.
10.3 Bias - The procedure in this test method has no bias because the value of oxidation stability can be defined only in terms of a test method.
11. Keywords
11.1 grease; oxidation