9. Calculation and Report
9.1 Calculate the acid number of the oil sample as follows:
where:
A = number of drops of the acid number reference solution in 8.5,
B = acid number of the acid number reference solution, and
C = number of drops of the oil sample (8.4).
9.2 Report the result as follows:
acid number, (Test Method D5770) = (result)
10. Precision and Bias
10.1 Precision - The precision of this test method was determined by statistical examination of interlaboratory test results over the acid number range from 0.06 to 1.1 mg KOH/g for nine samples analyzed by eight laboratories.
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:
0.20 x acid number
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:
0.70 x acid number
10.2 Bias - The procedures in this test method have no bias because the acid number can be defined only in terms of the test method.
11. Keywords
11.1 acid number; color indicator titration; oxidation testing; semiquantitative