ASTM D87 standard test method for melting point of petroleum wax (Cooling Curve)
9. Calculation and Report
9.1 Average the first five consecutive thermometer readings of the identified plateau, which agree within 0.1°C (0.2°F). Correct this average for error in the thermometer scale where necessary.
9.2 Report the result to the nearest 0.05°C (0.1°F) as the Petroleum Wax Melting Point (Cooling Curve), Test Method D87.
10. Precision and Bias
10.1 Precision - The precision of this test method as determined by statistical examination of interlaboratory results is as follows:
NOTE 5 - This method is considered suitable for waxes of melting point between 38°C (100°F) and 82°C (180°F). The precision data below were obtained in interlaboratory studies by ASTM Committee D-2 using waxes in 127 to 144°F range and by IP using waxes in 108 to 151°F range.
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:
0.1°C (0.2°F)
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:
0.5°C (1.0°F)
10.2 These precision values have been obtained by statistical examination of interlaboratory test results and were first published in 1965. These values are based on a study among 15 laboratories, using five paraffin waxes with a melting point range of 53 to 66°C (128 to 151°F).
10.3 Bias - The procedure in this test method for has no bias because the value of melting point can be defined only in terms of a test method.
11. Keywords
11.1 cooling curve; melting point; petroleum wax; wax
