ASTM D874 method for sulfated ash from lubricating oils and additives
11. Report
11.1 Report the result to the nearest 0.001 mass % for samples below 0.02 mass % and to the nearest 0.01 mass % for higher levels as the sulfated ash, Test Method D874.
12. Quality Control
12.1 Confirm the performance of the instrument or the test procedure by analyzing a QC sample (see 7.8).
12.1.1 When QC/Quality Assurance (QA) protocols are already established in the testing facility, these may be used to confirm the reliability of the test result.
12.1.2 When there is no QC/QA protocol established in the testing facility, Appendix X1 can be used as the QC/QA system.
13. Precision and Bias
13.1 The precision of this test method as determined by statistical examination of interlaboratory results is as follows:
13.1.1 For sulfated ash levels between 0.005 and 0.10 mass %.
13.1.1.1 Repeatability - The difference between two test results obtained by the same operator with the same apparatus under constant operating conditions on identical test materials 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:
r = 0.047 X(0.85)
where X = average of two results.
13.1.1.2 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 in only one case in twenty:
R = 0.189 X(0.85)
where X = average of two results.
13.1.1.3 Specimen data are shown in Table 1.
NOTE 11 - The precision values in the range from 0.005 to 0.10 mass % sulfated ash were obtained by statistical examination of interlaboratory test results obtained in a joint ASTM-IP cooperative program conducted in 1975. Only platinum dishes were used.
13.1.2 For sulfated ash levels between 0.11 and 25 mass %:
13.1.2.1 Repeatability - The difference between two test results obtained by the same operator with the same apparatus under constant operating conditions on identical test materials would, in the long run in the normal and correct operation of the test method, exceed the following values in only one case in twenty:
r = 0.060 X(0.75)
where X = average of two results.
13.1.2.2 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 in only one case in twenty:
R = 0.142 X(0.75)
where X = average of two results.
13.1.2.3 Specimen data are shown in Table 2.
NOTE 12 - The precision values in the range from 0.10 to 25 mass % sulfated ash were obtained by statistical examination of interlaboratory test results obtained in a joint ASTM-IP cooperative program conducted in 1981.
13.2 Bias - There is no accepted reference material suitable for determining the bias of the procedures in this test method for measuring ash.
14. Keywords
14.1 additives; ash; lubricating oils
