1.1 This test method covers the evaluation of the shear stability of hydraulic fluids in terms of the final viscosity that results from irradiating a sample of the hydraulic fluid in a sonic oscillator.
1.2 Evidence has been presented that a good correlation exists between the shear degradation that results from sonic oscillation and that obtained in a vane pump test procedure.2
1.3 This test method uses millimetres squared per second (mm2 /s), an SI unit, as the unit of viscosity. For information, the equivalent unit, cSt, is shown in parentheses.
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.
ASTM D5621-20 Referenced Document
ASTM D2603 Test Method for Sonic Shear Stability of Polymer-Containing Oils
ASTM D445 Standard Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (the Calculation of Dynamic Viscosity)
ASTM D6022 Standard Practice for Calculation of Permanent Shear Stability Index
ASTM D7042 Standard Test Method for Dynamic Viscosity and Density of Liquids by Stabinger Viscometer (and the Calculation of Kinematic Viscosity)*, 2021-11-01 Update
ASTM D5621-20 history
2020ASTM D5621-20 Standard Test Method for Sonic Shear Stability of Hydraulic Fluids
2019ASTM D5621-19 Standard Test Method for Sonic Shear Stability of Hydraulic Fluids
2007ASTM D5621-07(2013) Standard Test Method for Sonic Shear Stability of Hydraulic Fluids
2007ASTM D5621-07 Standard Test Method for Sonic Shear Stability of Hydraulic Fluids
2001ASTM D5621-01 Standard Test Method for Sonic Shear Stability of Hydraulic Fluid
1994ASTM D5621-94 Standard Test Method for Sonic Shear Stability of Hydraulic Fluid