ASTM D5773 Standard Test Method for Cloud Point of Petroleum Products and Liquid Fuels (Constant Cooling Rate Method)
12. Report
12.1 Report the temperature recorded in 11.10 as the automatic cloud point Test Method D5773.
12.2 When specified, round the temperature recorded in 11.10 to the next lower integer and report as the Test Method D2500 equivalent cloud point per Test Method D5773.
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 successive test results, obtained by the same operator using the same apparatus under constant operating conditions on identical test material, would in the long run, in the normal and correct operation ofthis test method, exceed 1.3 °C only in one case in twenty.
13.1.2 Reproducibility - The difference between two single and independent test results, obtained by different operators working in different laboratories on identical test material, would in the long run, in normal and correct operation of this test method, exceed 2.5 °C only in one case in twenty.
13.1.3 The precision statements were derived from a 1997 interlaboratory cooperative test program. Participants analyzed eleven sample sets as blind duplicates, comprised of various distillate fuels and lubricating oils, and with a cloud point range of +34 °C to -56 °C. Ten laboratories participated with the automatic apparatus and eight laboratories participated with the manual Test Method D2500/IP 219 test method. The precision statistics were compiled and calculated based on the 0.1 °C resolution offered by this automatic apparatus. Information on the type of samples and their average cloud points are in the research report.
13.2 Bias - Since there is no accepted reference material suitable for determining the bias for the procedure in this test method, bias has not been determined.
13.3 Relative Bias - The results of the interlaboratory program were examined for bias relative to Test Method D2500/IP 219. Astatistically insignificant bias of −0.03 °C was observed.
13.4 Precision ofBiodiesel Fuels - The precision ofthis test method, as determined by the statistical examination of the interlaboratory test results, is as follows:
13.4.1 Repeatability for Blends ofBiodiesel in Diesel - The difference between successive test results, obtained by the same operator, using 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 0.017 x (27 - X) °C only in 1 case in 20, where X is the average of results being compared.
13.4.2 Reproducibility for Blends of Biodiesel in Diesel - The difference between two single and independent test 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 0.063 x (27 - X) °C only in 1 case in 20, where X is the average of results being compared.
NOTE 6 - The precision for blends of biodiesel in diesel samples comprised cloud points from about -27.2 °C to 13.8 °C. Table 1 illustrates repeatability and reproducibility with a range of cloud point. The degrees of freedom associated with the reproducibility estimate from this round robin study is 23. Since the minimum requirement of 30 (in accordance with Practice D6300) is not met, users are cautioned that the actual repeatability/reproducibility may be significantly different than these estimates.
13.4.3 The precision statements were derived from a 2006 interlaboratory cooperative test program. Seven participants analyzed sample sets comprised of different biodiesel blends from various feedstocks, and included seasonal diesel samples and biodiesel blends B5, B10, and B20, as well as B100 including soy methyl ester (SME), yellow grease methyl ester (YGME), and tallow methyl ester (TME) with temperature range from -27.2 °C to 13.8 °C. Seven laboratories participated with the D5773/IP 446 test method. Information on the type of samples and their average cloud points are in the research report.
13.5 Bias of Biodiesel Fuels - Since there is no accepted reference material suitable for determining the bias for the procedure in this test method, bias has not been determined.
13.6 Relative Bias - The statistical analysis for the interlaboratory test program for bias relative to Test Method D2500/IP 219 has been determined for blends of biodiesel in diesel samples.
14. Keywords
14.1 automatic cloud point; cloud point; constant cooling rate; Peltier; petroleum products; thermoelectric; wax crystals
