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ASTM D6821-20a

Current Revision

Standard Test Method for Low Temperature Viscosity of Drive Line Lubricants in a Constant Shear Stress Viscometer

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1.1 This test method covers the measurement of the viscosity of drive line lubricants (gear oils, automatic transmission fluids, and so forth) with a constant shear stress viscometer at temperatures from –40 °C to 10 °C after a prescribed preheat and controlled cooling to the final test temperature. The precision is stated for test temperatures from –40 °C to –26 °C.

1.2 The applicability of this particular test method to petroleum products other than drive line lubricants has not been determined.

1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.3.1 This standard uses the SI based unit of milliPascal second (mPa·s) for viscosity which is equivalent to centiPoise (cP).

1.4 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.


5.1 Viscosity of drive line lubricants at low temperature is critical for both gear lubrication and the circulation of the fluid in automatic transmissions. For gear oils (GOs), the issue is whether the fluid characteristics are such that the oil will flow into the channel dug out by the submerged gears as they begin rotating and re-lubricating them as they continue to rotate. For automatic transmission fluids, torque, and tractor fluids the issue is whether the fluid will flow into a pump and through the distribution system rapidly enough for the device to function.

5.2 The low temperature performance of drive line lubricant flow characteristics was originally evaluated by the channel test. In this test, a pan was filled to a specified depth of approximately 2.5 cm and then cooled to test temperature. The test was performed by scraping a channel through the full depth of the fluid and across the length of the pan after it had soaked at test temperature for a specified time. The time it took the fluid to cover the channel was measured and reported. The channel test was replaced by Test Method D2983 in 1971.

5.3 The results of this test procedure correlate with the viscometric measurements obtained in Test Method D2983.4 The correlation obtained is:

Equation D6821-20A_8

where:

V   =   the apparent viscosity measured by this test method, and
VD2983   =   the apparent viscosity measured by Test Method D2983.

5.3.1 The equation was obtained by forcing the fit through zero. The coefficient of variation (R2) for this correlation is 0.9948.

SDO ASTM: ASTM International
Document Number D6821
Publication Date Nov. 1, 2020
Language en - English
Page Count 7
Revision Level 20a
Supercedes
Committee D02.07
Publish Date Document Id Type View
Nov. 1, 2020 D6821-20A Revision
June 1, 2020 D6821-20 Revision
June 1, 2018 D6821-18 Revision
May 1, 2017 D6821-17 Revision
July 1, 2014 D6821-14 Revision
Nov. 1, 2012 D6821-12 Revision
Aug. 10, 2002 D6821-02E01 Revision
Aug. 10, 2002 D6821-02 Revision
Nov. 1, 2007 D6821-02R07 Reaffirmation