Standard Active Last Updated: Jul 26, 2022 Track Document
ASTM D6351-22

Standard Test Method for Determination of Low Temperature Fluidity and Appearance of Hydraulic Fluids

Standard Test Method for Determination of Low Temperature Fluidity and Appearance of Hydraulic Fluids D6351-22 ASTM|D6351-22|en-US Standard Test Method for Determination of Low Temperature Fluidity and Appearance of Hydraulic Fluids Standard new BOS Vol. 05.02 Committee D02
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Significance and Use

4.1 The temperature at which a lubricant remains fluid and homogeneous after seven days is an index of its ability to withstand prolonged exposure to cold temperature. With vegetable oils and some synthetic esters, it is necessary to do extended cold storage testing. Quick cool, short-term tests, such as Test Methods D97 and D2500, do not adequately predict the tendency to solidify over longer time spans at cold temperatures.

4.2 This test method is not intended to indicate cold temperature pumpability performance. A separate assessment of viscometric performance should be made in order to assess cold flow properties, which are important in order to avoid system damage in cold temperature applications. Suitable guidelines for such testing and test temperatures for various viscosity grades can be found in Practice D6080.

4.3 No specific temperature of measurement is given in this test method because fluids with different viscosity grades have different cold temperature performance expectations. For guidance on temperature selection relative to an intended low temperature viscosity grade or ISO VG, consult Practice D6080. As an example of using Practice D6080, a L22 viscosity grade would be evaluated at the lowest temperature for that grade, namely –22.9 °C. Alternatively, a fluid can be evaluated at the lowest temperature expected for field service.


1.1 This test method covers the fluidity and appearance of hydraulic fluids after storage at low temperature.

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

1.2.1 Exception—In 6.1.1, the material is designated in cSt as this is the common name used for this type of oil.

1.3 WARNING—Mercury has been designated by many regulatory agencies as a hazardous substance that can cause serious medical issues. Mercury, or its vapor, has been demonstrated to be hazardous to health and corrosive to materials. Use caution when handling mercury and mercury-containing products. See the applicable product Safety Data Sheet (SDS) for additional information. The potential exists that selling mercury or mercury-containing products, or both, is prohibited by local or national law. Users must determine legality of sales in their location.

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. For specific warning statements, see 1.3 and Section 6.

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.

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Book of Standards Volume: 05.02
Developed by Subcommittee: D02.N0
Pages: 3
DOI: 10.1520/D6351-22
ICS Code: 75.120