ASTM D7154 Test Method for Freezing Point of Aviation Fuels (Automatic Fiber Optical Method)
12. Report
12.1 Report the temperature of crystal disappearance recorded in 11.5 to the nearest 0.1 °C as the freezing point, Test Method D7154.
13. Precision and Bias
13.1 Precision - The precision of this test method as determined by the statistical examination of the interlaboratory test results is as follows:
13.1.1 Repeatability - The difference between two 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 0.5 °C only in one case in twenty.
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, in the normal and correct operation of this test method, exceed 1.9 °C only in one case in twenty.
13.2 Bias - Because there are no liquid hydrocarbon mixtures of known freezing point, which simulate aviation fuels, bias cannot be established.
13.3 Relative Bias - The degree of agreement between this test method and Test Method D2386 from the 2003 interlaboratory program cited has been performed in accordance with Practice D6708. No relative bias was observed. The cross method reproducibility (Rxy) identified in the research report between this test method and Test Method D2386 is 2.2.
13.4 The precision statements were derived from a 2003 interlaboratory cooperative test program. Participants analyzed 13 samples sets comprised of various aviation fuels over the temperature range of -60 °C to -42 °C. Eleven laboratories participated with the automatic fiber optical method and fifteen with the manual Test Method D2386 or IP 16 test methods. The precision statistics were compiled and calculated based on the 0.1 °C resolution offered by the automatic fiber optical method. Information on the types of samples and their respective average freezing point is contained in the research report.
14. Keywords
14.1 automatic freezing point; automatic fiber optical method; aviation gasoline; aviation turbine fuels; freezing point
