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    ASTM D6821 - 20a

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

    Active Standard ASTM D6821 | Developed by Subcommittee: D02.07

    Book of Standards Volume: 05.03

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    Significance and Use

    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


    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.

    1. Scope

    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.

    2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

    ISO Standards

    ISO 17025

    ISO Guide 34

    ASTM Standards

    D2983 Test Method for Low-Temperature Viscosity of Automatic Transmission Fluids, Hydraulic Fluids, and Lubricants using a Rotational Viscometer

    D3829 Test Method for Predicting the Borderline Pumping Temperature of Engine Oil

    D4684 Test Method for Determination of Yield Stress and Apparent Viscosity of Engine Oils at Low Temperature

    D6896 Test Method for Determination of Yield Stress and Apparent Viscosity of Used Engine Oils at Low Temperature

    D8278 Specification for Digital Contact Thermometers for Test Methods Measuring Flow Properties of Fuels and Lubricants

    E563 Practice for Preparation and Use of an Ice-Point Bath as a Reference Temperature

    ICS Code

    ICS Number Code 75.100 (Lubricants, industrial oils and related products)

    UNSPSC Code

    UNSPSC Code 15120000(Lubricants and oils and greases and anti corrosives); 41103312(Viscosimeters)

    Referencing This Standard
    Link Here
    Link to Active (This link will always route to the current Active version of the standard.)

    DOI: 10.1520/D6821-20A

    Citation Format

    ASTM D6821-20a, Standard Test Method for Low Temperature Viscosity of Drive Line Lubricants in a Constant Shear Stress Viscometer, ASTM International, West Conshohocken, PA, 2020, www.astm.org

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