ASTM D6895 Standard Test Method for Rotational Viscosity of Heavy Duty Diesel Drain Oils at 100°C
4. Summary of Test Method
4.1 The sample is placed in a controlled stress or controlled shear rate rheometer/viscometer at 100°C. The sample is presheared at 10 s(-1) for 30 s followed by heating at 100°C for 10 min. An increasing shear rate (approximately 10 to 300 s(-1)) or shear stress (0.1 to 10 Pa) sweep is run followed by a decreasing sweep. The rotational viscosity for each step (increasing and decreasing) at 100 s(-1) shear rate is interpolated from the viscosity versus shear rate data table. The rate index, as a measure of shear thinning, is calculated from a plot of ln (shear stress) versus ln (shear rate).
5. Significance and Use
5.1 Rotational viscosity measurements allow the determination of the non-Newtonian, shear thinning property of drain oil. Rotational viscosity values can be compared at a shear rate of 100 s(-1) by this test method.
