ASTM D5133 low temp, low shear rate, viscosity/temp dependence of lubricants
ASTM D5133 standard test method for Low Temperature, Low Shear Rate, Viscosity/Temperature Dependence of Lubricating Oils Using a Temperature-Scanning Technique
14. Report
14.1 Report to the nearest tenth of a degree the temperature associated with each of the following viscosities:
5000, 10 000, 20 000, 30 000, 40 000 mPa•s (cP).
14.2 If there is a critical pumpability viscosity chosen as a criterion by the user of the test method, then report to the nearest tenth of a degree Celsius the critical pumpability temperature associated with it
NOTE 11 - Past work has indicated that, using this test method, either 40 000 or 30 000 mPa•s (cP) are indicative of engine pumpability requirements, depending on the engine manufacturer.
14.3 If the Gelation Index is greater than or equal to 6.0, report the Gelation Index to the nearest tenth of a unit, and the Gelation Index temperature to the nearest Celsius degree. If the Gelation Index is less than 6.0 report the value as less than 6.0 and do not report Gelation Index temperature.
NOTE 12 - However, the test method generates values of Gelation Index values below 6 and these are useful in appraising instrument and operator consistency as well as providing other information.
15. Precision and Bias
15.1 The precision for critical pumpability temperatures derived from this round robin are as follows:
15.1.1 Repeatability - The difference between successive results obtained by the same operator with the same apparatus under constant operating conditions on identical test materials would, in the long run, in the normal and correct operation of the test method, exceed the following value in only one case in twenty:
Repeatability, 0.5 °C
15.1.2 Reproducibility - The difference between two single and independent results obtained by different operators working in different laboratories on identical test materials would, in the long run, in the normal and correct operation of the test method, exceed the following value in only one case in twenty:
Reproducibility, 1.4 °C
15.2 The precision for Gelation Index derived from this round robin are as follows:
15.2.1 Repeatability - The difference between successive results obtained by the same operator with the same apparatus under constant operating conditions on identical test materials would, in the long run, in the normal and correct operation of the test method, exceed the following value in only one case in twenty:
Repeatability (Gelation Index) - 16 % of the mean value.
15.2.2 Reproducibility - The difference between two single and independent results obtained by different operators working in different laboratories on identical test materials would, in the long run, in the normal and correct operation of the test method, exceed the following value in only one case in twenty:
Reproducibility (Gelation Index) - 29 % of the mean value
15.3 The precision for Gelation Index temperature derived from this round robin is as follows:
15.3.1 Repeatability - For oils with Gelation Index values greater than 6, the difference between successive results obtained by the same operator with the same apparatus under constant operating conditions on identical test materials would, in the long run, in the normal and correct operation of the test method, exceed the following value in only one case in twenty:
Repeatability (Gelation Index temperature) 2 °C
15.3.2 Reproducibility - For oils with Gelation Index values greater than 6, the difference between two single and independent results (larger minus smaller) obtained by different operators working in different laboratories on identical test materials would, in the long run, in the normal and correct operation of the test method, exceed the following value in only one case in twenty:
Reproducibility (Gelation Index temperature) 2 °C
15.4 The interlaboratory program documented in RRD02-1448 included eight oils tested in 19 laboratories. The samples measured in the study covered the ranges of 5 000 to 40 000 mPa(s), 4.5 to 38.2 Gelation Index and -18.0 to -31.0 °C Gelation Index temperature.
15.5 The precision for viscosity derived from this round robin is as follows:
15.5.1 The difference between successive results obtained by the same operator with the same apparatus under constant operating conditions of identical test materials would, in the long run, in the normal and correct operation of the test method, exceed the following value in only one case in twenty:
Repeatability (Viscosity) = 16% of the mean value
15.5.2 The difference between two single and independent results obtained by different operators working in different laboratories on identical test materials would, in the long run, in the normal and correct operation of the test method, exceed the following value in only one case in twenty:
Reproducibility (Viscosity) = 26% of the mean value
15.6 The interlaboratory program documented in RR:D02-1511 included eight oils tested in 13 laboratories. The samples measured in the study covered the viscosity range from 5000 to 40 000 mPa(s).
15.7 Since there is no accepted reference material suitable for determining the bias for this test method, no statement on bias is being made.
16. Keywords
16.1 borderline pumping temperature; critical pumpability temperature; critical pumpability viscosity; engine oil; gelation; Gelation Index; Gelation Index temperature; low-temperature engine oil pumpability; low-temperature rheology; Scanning Brookfield technique; temperature-scanning technique; viscosity
