ASTM D664 for acid number of petroleum products
ASTM D664 for acid number of petroleum products by potentiometric titration
14. Report
14.1 Given there are two different ways to determine the endpoint, report the type of endpoint used: inflection point or buffer endpoint. Report sample size used if differs from the recommended sample size. Also, report if chloroform was used as solvent. Report the results as acid number or strong acid number as follows:
Acid number (Test Method D664) = (result)
Strong acid number (Test Method D664) = (result)
14.2 For used oil samples report also the date of testing and, when available, the date the sample was taken (see 10.2).
15. Precision and Bias
15.1 Acid Number:
15.1.1 Repeatability - The difference between successive 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.
Fresh Oils = 0.044(X + 1)
Used Oils Buffer end point = 0.117 X
where:
X = the average of the two test results.
15.1.2 Reproducibility - he 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.
Fresh Oils = 0.141(X + 1)
Used Oils Buffer end point = 0.44X
where:
X = the average of the two test results.
15.2 Strong Acid Number:
15.2.1 Precision data have not been developed for strong acid number because of its rare occurrence in sample analysis.
15.3 Bias - The procedures in this test method have no bias because the acid values can be defined only in terms of the test method.
16. Keywords
16.1 acid number; lubricants; petroleum products; potentiometric; strong acid number; titration
