ASTM D2638 Test Method for Real Density of Calcined Petroleum Coke by Helium Pycnometer
12. Report
12.1 Report to the third decimal place the real density as calculated in 11.1.
13. Precision and Bias
13.1 The values in the statements were determined in a cooperative program following Practice E691. In this 2008 study, there were twelve laboratories and eight samples. The precision of this test method as determined by the statistical examination of interlaboratory test results is as follows:
13.1.1 Repeatability - The difference between successive results by the same operator using the same apparatus under constant operating conditions on the identical test materials, will in the long run, in normal and correct operation of the test method, exceed the following values only in one case in twenty:
Repeatability = 0.005 g/cm3
13.1.2 Reproducibility - The difference between two single and independent results obtained by different laboratories on identical test materials will in the long run, in normal and correct operation of the test method, exceed the following values only in one case in twenty:
Reproducibility = 0.013 g/cm3
13.1.3 Bias - Since there is no accepted reference material suitable for determining the bias for the procedure in this test method for measuring the real density of calcined petroleum coke, no statement on bias is being made.
NOTE 3 - The reproducibility value reflects the overall reproducibility covering all makes of pycnometers used in this work.
14. Keywords
14.1 calcined petroleum coke; helium pycnometer; real density
