ASTM D6660 for Freezing Point of Aqueous Ethylene Glycol Base Engine Coolants
ASTM D6660 Standard Test Method for Freezing Point of Aqueous Ethylene Glycol Base Engine Coolants by Automatic Phase Transition Method
11. Report
11.1 Report the temperature recorded in 10.7 as the freezing point, Test Method D6660.
12. Precision and Bias
12.1 Precision - The precision of this test method as determined by the statistical examination of the interlaboratory test results is as follows:
12.1.1 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 the test method, exceed 0.6°C (1.1°F) only in one case in twenty.
12.1.2 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 the test method, exceed 0.8°C (1.4°F) only in one case in twenty.
12.2 Relative Bias - The automatic method displayed a mean bias of 0.67 °C relative to the manual procedure, Test Method D1177. It is not statistically significant at the 95 % confidence level.
The precision statements were derived from a 1999 interlaboratory cooperative test program. Participants analyzed 5 sample sets comprised of ethylene glycol base coolant the concentration range of 40 to 60 volume in 5 % volume increments. Eight laboratories participated with the automatic phase transition apparatus and seven participated with the manual D1177 test method. The interlaboratory program was conducted double blind. Two analysts measured different sets of samples by each method at seven of the laboratories. One laboratory performed only the automatic method. Each laboratory received two sets of randomized samples labelled A though E and 1 to 5. A total of twenty five repeat measurements were distributed over the laboratories. 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 aqueous engine coolants; crystals; engine coolants; freezing point; Peltier; thermoelectric
