ASTM D1092 test method for measuring apparent viscosity of lubricating greases
11. Precision and Bias
11.1 Due to the nature of the results, the precision of this test method was not obtained according to RR:D02-1007 "Manual on Determining Precision Data for ASTM Methods on Petroleum Products and Lubricants". The precision of this test method as determined by statistical examination of interlaboratory results is as follows:
11.2 The data in 11.2.1 and 11.2.2 should be used for judging the acceptability of results (95 % confidence) according to the concept of precision as given in Practice D3244.
11.2.1 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 values given in Table 2 only in one case in twenty.
11.2.2 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 values given in Table 2 only in one case in twenty.
11.2.3 Reproducibility of the curve drawing operation varies from 5 to 8 % for the above samples. These data are based upon curve values of apparent viscosity at the six shear rates. A separate curve was drawn for each run.
11.3 Bias - Since there is no accepted reference material suitable for determining the bias for the procedure in Test Method D1092, bias has not yet been determined.
11.4 There is no research report on Test Method D1092 because this test method was developed before research report guidelines were instituted, and are no longer available.
12. Keywords
12.1 apparent viscosity; capillary; lubricating grease; shear rate; viscosity
