ASTM International - ASTM D5133-05(2011)
Standard Test Method for Low Temperature, Low Shear Rate, Viscosity/Temperature Dependence of Lubricating Oils Using a Temperature-Scanning Technique
|Publication Date:||1 January 2011|
|ICS Code (Lubricants, industrial oils and related products):||75.100|
significance And Use:
Significance of Low-Temperature, Low Shear Rate, Engine Oil Rheology-The low-temperature, low-shear viscometric behavior of an engine oil determines whether the oil will flow to the sump inlet... View More
Significance of Low-Temperature, Low Shear Rate, Engine Oil Rheology-The low-temperature, low-shear viscometric behavior of an engine oil determines whether the oil will flow to the sump inlet screen, then to the oil pump, then to the sites in the engine requiring lubrication in sufficient quantity to prevent engine damage immediately or ultimately after cold temperature starting.
Two forms of flow problems have been identified, flow-limited and air-binding behavior. The first form of flow restriction, flow-limited behavior, is associated with the oil's viscosity; the second, air-binding behavior, is associated with gelation.
Significance of the Test Method-The temperature-scanning
Note 1-This test method is one of three related to pumpability related problems. Measurement of low-temperature viscosity by the two other pumpability Test Methods D3829 and D4684, hold the sample in a quiescent state and generate the apparent viscosity of the sample at shear rates ranging up to 15 sec-1 and shear stresses up to 525 Pa at a previously selected temperature. Such difference in test parameters (shear rate, shear stress, sample motion, temperature scanning, and so forth) can lead to differences in the measured apparent viscosity among these test methods with some test oils, particularly when other rheological factors associated with gelation are present. In addition, the three methods differ considerably in cooling rates.
Gelation Index and Gelation Index Temperature-This test method has been further developed to yield parameters called the Gelation Index and Gelation Index temperature. The first parameter is a measure of the maximum rate of torque increase caused by the rheological response of the oil as the oil is cooled slowly. The second parameter is the temperature at which the Gelation Index occurs.View Less
1.1 This test method covers the measurement of the apparent viscosity of engine oil at low temperatures.
1.2 A shear rate of approximately 0.2 s-1 is produced at shear stresses below 100 Pa. Apparent viscosity is measured continuously as the sample is cooled at a rate of 1°C/h over the range −5 to −40°C, or to the temperature at which the viscosity exceeds 40 000 mPa·s (cP).
1.3 The measurements resulting from this test method are viscosity, the maximum rate of viscosity increase (Gelation Index), and the temperature at which the Gelation Index occurs.
1.4 Applicability to petroleum products other than engine oils has not been determined in preparing this test method.
1.5 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.