ASTM D3948 Determining Water Separation Characteristics of Aviation Turbine Fuels
ASTM D3948 Standard Test Method for Determining Water Separation Characteristics of Aviation Turbine Fuels by Portable Separometer
11. Report
11.1 Report the results obtained in 10.17.1 as the MSEP-A rating for Mode A operation or MSEP-B rating for Mode B operation.
12. Precision and Bias
12.1 MSEP-A ratings obtained using Mode A operation have precision as determined by the ten operator/instrument pairs on identical fuel samples at a common site, as follows:
12.1.1 Repeatability - The difference between successive measured MSEP-A 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 8).
NOTE 8 - These results are based on a 1983 ten laboratory cooperative test program using reference fuels and 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.
The need for additional cooperative testing to establish reproducibility when samples are shipped between laboratories (and therefore may not be identical at the time of testing) is being studied.
12.1.1.1 Reference Fuels - The repeatability of MSEP-A ratings for Jet A, Jet A-1, MIL JP 5, MIL JP 7, and MIL JP 8 reference fuels is shown in Fig. 9 (Note 9). These data were obtained using Mode A of the Mark V instrument.
NOTE 9 - This result is based on a 1978, eight laboratory cooperative test program using reference fluids prepared in accordance with Appendix X1.
12.1.1.2 Field Samples - The repeatability of MSEP-A ratings for Jet A, Jet A-1, MIL JP 5, MIL JP 7, and MIL JP 8 field samples, obtained by using test Mode A of the Mark V instruments, is shown in Fig. 10 (Note 10).
NOTE 10 - These results are based on a 1983, ten laboratory cooperative test program using Type A (field samples of MIL JP 5) fuels containing fuel system corrosion and icing inhibitors. 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.
12.1.2 Reproducibility - The difference between two single and independent measurements of MSEP-A 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 8).
12.1.2.1 Reference Fuels - The reproducibility of MSEP-A ratings for Jet A, Jet A-1, MIL JP 5, MIL JP 7, and MIL JP 8 reference fuels is shown in Fig. 9 (Note 9).
12.1.2.2 Field Samples - The reproducibility of MSEP-A ratings for Jet A, Jet A-1, MIL JP 5, MIL JP 7, and MIL JP 8 field samples using test Mode A of the Mark V instruments is shown in Fig. 9 (Note 10).
12.2 MSEP-B ratings obtained using Mode B operation have precision as determined by the ten operator/instrument pairs on identical fuel samples at a common site, as follows:
12.2.1 Repeatability - The difference between successive measured MSEP-B ratings obtained by the same operator with the same Micro-Separometer under constant operating conditions on identical MIL JP 4 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 8).
12.2.1.1 Reference Fuels - The repeatability of MSEP-B ratings for MIL JP 4 reference fuels is nine (maximum difference between two consecutive measurements obtained by the same operator using the same instrument) (Note 11).
12.2.1.2 Field Samples - The repeatability of MSEP-B ratings for MIL JP 4 field samples is 16 (maximum difference between two consecutive measurements obtained by the same operator using the same instrument) (Note 12).
12.2.2 Reproducibility - The difference between two single and independent measurements of MSEP-B ratings obtained by different operator/instrument pairs at the same location on identical MIL JP 4 test material would, in the long run, in the normal and correct operation of the test methods, exceed the following values for only one case in twenty (Note 6).
12.2.2.1 Reference Fuels - The reproducibility of MSEP-B ratings for MIL JP 4 reference fuels is ten (maximum difference between two measurements obtained by two different operators on the identical test sample using two different instruments at the same test site) (Note 11).
12.2.2.2 Field Samples - The reproducibility of MSEP-B ratings for MIL JP 4 field samples is 19 (maximum difference between two measurements obtained by two different operators on the identical test sample using two different instruments at the same test site) (Note 12).
NOTE 11 - This result is based on a 1983 ten-laboratory cooperative test program using MIL JP 4 fuels as a reference fuel prepared in accordance with Appendix X1.
NOTE 12 - This result is based on a 1983 ten-laboratory cooperative test program using field samples of MIL JP 4 fuels containing fuel system corrosion and icing inhibitors. The fuels did not contain any significant amounts of static dissipator additives (SDA). 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, on which data could be generated, using this test method correctly, that may not fall within the expected limits.
12.3 Bias - The procedure in this test method has no bias, because the value of MSEP is defined only in terms of this method.
13. Keywords
13.1 aviation turbine fuel; coalescence; jet fuel coalescer; MSEP rating; surfactant; water separation
