ASTM D938 Method for Congealing Point of Petroleum Waxes, Including Petrolatum
8. Report
8.1 Report the average of the multiple determinations as the congealing point, shown to the nearest 0.2°C (0.5°F).
9. Precision and Bias
9.1 The precision of this test method is not known to have been obtained in accordance with RR:D02-1007 "Manual on Determining Precision Data for ASTM Methods on Petroleum Products".
9.2 The precision of this test method as determined by statistical examination of interlaboratory results is as follows:
9.2.1 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:
Distillate waxes: 0.5°C (1.0°F)
Residual waxes, including petrolatums: 1.0°C (2.0°F)
9.2.2 Reproducibility - e 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:
Distillate waxes: 1.5°C (2.5°F)
Residual waxes, including petrolatums: 2.5°C (4.5°F)
9.3 Bias - The procedure in this test method for measuring the congealing point of petroleum waxes has no bias because the value of the congealing point can be defined only in terms of a test method.
10. Keywords
10.1 congealing point; petrolatum; petroleum waxes
