ASTM D5972 Freezing Point of Aviation Fuels (Automatic Phase Transition Method)
11. Report
11.1 Report the temperature recorded in 10.7 as the freezing point, Test Method D5972.
12. Precision and Bias
12.1 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 this test method, exceed 0.69°C only in one case in twenty.
12.1.1 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 this test method, exceed 1.30°C only in one case in twenty.
12.2 Bias - Because there are no liquid hydrocarbon mixtures of known freezing point, which simulate aviation fuels, bias cannot be established.
12.3 Relative Bias - The results for all the samples from the interlaboratory program were examined for biases relative to Test Method D2386. Some differences were observed for some fuels, but there was no consistent bias among all the fuels. All the differences were within the reproducibility of Test Method D2386 (2.5°C) except for two. These two were the only samples of fuels of Grades JP4 and Jet B, and for these the average results were 2.5°C and 2.8°C warmer than those of Test Method D2386. Therefore, the user should exercise appropriate caution when this test method is used in testing Jet B and JP4 samples.
12.4 The precision statements were derived from a 1994 interlaboratory cooperative test program. Participants analyzed 14 sample sets comprised of various aviation fuels over the temperature range of -45 to -65°C. Nine laboratories participated with the automatic phase transition apparatus and 15 participated with the manual Test Method D2386 test method. The precision statistics were compiled and calculated based on the 0.1°C resolution offered by the automatic phase transition method. Information on the types of samples and their respective average freezing point is contained in the research report.
13. Keywords
13.1 aviation turbine fuels; freezing point; Peltier; thermoelectric; wax crystals
