ASTM D7224 Standard Test Method for Determining Water Separation Characteristics of Kerosine-Type Aviation Turbine Fuels Containing Additives by Portable Separometer
14. Report
14.1 Report the results obtained in 13.18.1 as the MSEP rating, and reference this test method.
15. Precision and Bias
15.1 MSEP ratings obtained by this test method have precision as determined by round robin programs conducted at a common site, as follows:
NOTE 12 - These results are based on an eight operator cooperative test program conducted in March 2002, using a combination of ten samples consisting of a base fuel, two reference fuels, and seven field samples. The repeatability and reproducibility values were estimated from results obtained at the same location and on several consecutive days, by different operator/instrument pairs testing identical samples. Results, particularly for reproducibility, obtained at different times and locations may, therefore, not be comparable according to these estimates, since they may contain errors due to sampling and environmental factors. In practice, two results obtained at different laboratories (locations) would be acceptable if their difference did not exceed the published reproducibility. In the event that the difference did exceed the reproducibility, there would be no means of testing whether the results were acceptable or not.
15.1.1 Repeatability - The difference between successive measured MSEP ratings obtained by the same operator with the same Micro-Separometer under constant operating conditions on identical test material would, in the long run and in the normal and correct operation of the test method, exceed the following values for only one case in twenty (Note 13).
15.1.1.1 Reference Fuels - The repeatability of MSEP ratings for Jet A, Jet A-1, JP-5, JP-7, and JP-8 reference fuels is shown in Fig. 13 (Note 13).
NOTE 13 - This repeatability is based on a 1983 eight laboratory cooperative test program using reference fluids prepared in accordance with Appendix X1. This data was used because the MCell Coalescer with the aluminum syringe has repeatedly demonstrated that the MSEP results for reference fluids are the same as those obtained by performing MSEP tests according to Test Method D3948 using the Alumicel Coalescer (TM) and plastic syringe. This was substantiated from the data obtained in the March 2002 program.
15.1.1.2 Field Samples - The repeatability of MSEP ratings for Jet A, Jet A-1, JP-5, JP-7, and JP-8 field samples, obtained by using test Mode A of the Mark V Deluxe instruments, is shown in Fig. 14 (Note 14).
NOTE 14 - These results are based on a March 2002, eight laboratory cooperative test program using ten samples, seven of which were field samples containing various concentrations and combinations of typical additives. Due to the large number of additive combinations and concentrations, there may be field samples other than those used to develop the precision of this test method that may not respond within the expected limits.
15.1.2 Reproducibility - The difference between two single and independent measurements of MSEP rating obtained by different operator/instrument pairs at the same location on identical test material would, in the long run, in the normal and correct operation of the test method, exceed the following values for only one case in twenty (Note 12).
15.1.2.1 Reference Fuels - The reproducibility of MSEP ratings for Jet A, Jet A-1, JP-5, JP- 7, and JP-8 reference fuels is shown in Fig. 13 (Note 13).
15.1.2.2 Field Samples - The reproducibility of MSEP ratings for Jet A, Jet A-1, JP-5, JP-7, and JP-8 field samples using this test method is shown in Fig. 14 (Note 14).
15.2 Bias - The procedure in this test method has no bias, because the value of MSEP is defined only in terms of this test method.
15.3 Relative Bias - There is no statistically significant relative bias between this test method and Test Method D3948 for clean fuels (with high MSEP results) and for fuels containing strong surfactants such as reference fuels (with low MSEP results). For fuels containing weak surfactants, such as approved additives like static dissipator additive and corrosion inhibitor, Test Method D3948 typically gives lower MSEP results relative to this test method.
16. Keywords
16.1 additives; aviation turbine fuel; coalescence; jet fuel; micro-separometer; MSEP rating; surfactant; water separation
