ASTM D5621 Standard Test Method for Sonic Shear Stability of Hydraulic Fluids
5. Apparatus
5.1 Sonic Shear Unit, fixed frequency oscillator and sonic horn.
5.2 Auxiliary Equipment - To facilitate uniform performance, the following auxiliary equipment is recommended:
5.2.1 Cooling Bath or Ice Bath, to maintain a jacket temperature of 0°C.
5.2.2 Griffin 50-mL Beaker, borosilicate glass.
5.2.3 Sonic-Insulated Box, to enclose the sonic horn to reduce the ambient noise level produced by the sonic shear unit.
5.3 Viscometer, any viscometer and bath meeting the requirements of Test Method D445.
6. Reference Fluids
6.1 The reference fluid is ASTM Reference Fluid B, a petroleum oil containing a polymer capable of being broken down by turbulence at high rates of shear. This oil has a viscosity of about 13.6 mm2/s (cSt) at 40°C. The viscosity of a specific lot is supplied by the provider of that lot.
