ASTM D2068 Test Method for Filter Plugging Tendency of Distillate Fuel Oils
11. Report
11.1 Report the results of the test in one of the following forms:
11.1.1 If undissolved water is found in 9.3, report Undissolved Water Present, Test Not Carried Out.
11.1.2 Filter plugging tendency (FPT) as calculated in 10.1 from:
11.1.2.1 Maximum pressure (P) reading obtained for 300 mL of fuel to pass the filter, in the form XkPa/300 mL, or
11.1.2.2 Volume of fuel (V) passed at a pressure reading of 105 kPa, in the form 105 kPa/Y mL. If condition of 9.6, Note 4 applies, the words high initial pressure are appended to the results.
11.2 For every test, report the initial pressure recorded in 9.6 and the temperature recorded in 9.3.
12. Precision and Bias
12.1 Precision - The following criteria should be used for judging the acceptability of results (95 % probability):
12.1.1 Repeatability - The difference between two results obtained by the same operator on 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:
0.277 (FPT - 1)
where:
FPT = the normalized result calculated as in 10.1.
12.1.2 Reproducibility - The difference between two single and independent results obtained by different operators working in different laboratories 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:
1.405 (FPT - 1)
where:
FPT = the normalized result calculated as in 10.1.
NOTE 5 - These precision values have been obtained by statistical examination of inter-laboratory results on a matrix of twelve laboratories testing six fuels covering a range of FPT from 1.01 to 6.5. They were first published in 1989.
12.2 Bias - The procedure in this test method for measuring the filter plugging tendency of gas oils and distillate diesel fuels has no bias because the value of the filter plugging tendency can be defined only in terms of a test method.
13. Keywords
13.1 filterability; distillate fuels; gas oils; fuel filterability; fuel cleanliness
