12. Calculation and Report
12.1 Subtract the initial mass of the test membrane filter, W1, from the final mass, W2.
12.2 Subtract the initial mass of the control membrane filter, W3, from the final mass, W4.
12.3 Divide the correct mass of contaminant (W2 - W1) - (W4 - W3) by the volume of sample filtered and report the result as total contaminant, expressed in milligrams per litre.
NOTE 6 - If matched-weight membrane filters have been used for the test (see Note 1), then W1 = W3 and the corrected mass of contaminant in 12.3 becomes W2 - W4.
12.4 Report the result to the nearest 0.01 mg/L, and also the sample volume used in the test.
13. Precision and Bias
13.1 The precision of this test method is not known to have been obtained in accordance with currently accepted guidelines in Committee D-2 RR:D02-1007.
13.2 These precision data have been obtained by statistical examination of test results using 5-L samples and were first published in 1966.
13.3 Repeatability - The difference between successive 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 in only one case in twenty:
where x is the average value of two results.
13.4 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, exceed the following values in only one case in twenty:
where x is the average value of two results.
13.5 Typical values are given in Table 1.
NOTE 7 - Reproducibility values were determined through cooperative testing by different operators using separate apparatus working at the same location using identical test material. This procedure was adopted as it is highly improbable, if not impossible, to ensure the obtaining of "identical test material" when testing at different locations.
13.6 Bias - The procedure given for the determination of particulate contaminant in aviation turbine fuels has no bias since this property can only be defined in terms of this test method.
14. Keywords
14.1 aviation fuel; color rating; field monitor; gravimetric contaminant; membrane color; membrane filter; particulate