ASTM D5621 Standard Test Method for Sonic Shear Stability of Hydraulic Fluids
3. Summary of Test Method
3.1 A convenient volume of hydraulic fluid is irradiated in a sonic oscillator for a period of time and the change in viscosity is determined by Test Method D445. A standard reference fluid containing a readily sheared polymer is run frequently to ensure that the equipment imparts a controlled amount of sonic energy to the sample.
3.2 The conditions to obtain the data for the precision statement were: 30 mL sample, 12.5 min calibration, and 40 min sample irradiation at 0°C jacket temperature.
4. Significance and Use
4.1 This test method was developed using Test Method D2603-91.
4.2 This test method permits the evaluation of shear stability with minimum interference from thermal and oxidative factors that may be present in some applications. It has been found applicable to fluids containing both readily sheared and shear-resistant polymers. Correlation with performance in the case of hydraulic applications has been established.
