ASTM D5621 Standard Test Method for Sonic Shear Stability of Hydraulic Fluids
8. Procedure
8.1 Clean the sonic horn using a lintless wiper and optional solvent and calibrate the apparatus as described in 7.3. Introduce 30 mL of the hydraulic fluid sample to be tested into a clean 50-mL Griffin beaker and immerse in the constant temperature bath at 0°C. The beaker should be in a vertical position. Allow the sample to equilibrate for 12.5 min. Immerse the sonic horn in the fluid as described in 7.3. Irradiate the sample for 40 min at exactly the same power setting determined in 7.3. Upon completion of irradiation, remove the sample and clean the sonic horn in preparation for the next run.
8.2 Determine the viscosity of the sample by Test Method D445 before and after irradiation.
