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 Calculate total contaminant in milligrams per litre as follows:
(W2 - W1) - (W4 - W3)/Volume filtered, L
NOTE 9 - If matched-weight membranes have been used for the test (see Note 1), then W1 = W3 and the corrected weight of contaminant in 12.3 becomes W2 - W4.
12.4 Report the particulate contamination to the nearest 0.01 mg/L, and also report the sample volume used in the test.
13. Precision and Bias
13.1 The precision of this test method as determined by interlaboratory results is as follows:
13.1.1 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 = the mean of the two results.
13.1.2 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, exceed the following values in only one case in twenty:
where:
x = the mean of the two results.
13.1.3 Repeatability and reproducibility values for various values of x are given in Table 1.
13.2 Bias - The procedure given for the determination of particulate contamination in aviation turbine fuel by laboratory filtration has no bias since this property can be defined only in terms of a test method.
14. Keywords
14.1 aviation fuel; gravimetric contaminant; membrane ncolor; membrane filter; particulate