ASTM D2162 Test Method for Basic Calibration of Master Viscometers and Viscosity Oil Standards
9. Calibration of Viscosity Oil Standards at 40°C
9.1 Choose an oil with a kinematic viscosity of about 3 mm2/s (cSt/s) at 40°C. Filter a portion into a clean beaker through a 200-mesh (75-µm) sieve, or other suitable filter, to remove dirt or sediment. If necessary, adjust the temperature of the oil to within 3°C of 20°C.
9.2 Adjust the temperature of the bath to 40 +/- 0.01°C applying the necessary thermometer corrections.
NOTE 6 - The procedure is given for 40°C because kinematic viscosities of petroleum oils are traditionally measured at this temperature and so viscosity oil standards at 40°C are in common use. Master viscometers may, however, be calibrated at any convenient bath temperature and used, with any necessary corrections, at other temperatures.
9.3 Charge one of the master viscometers, already calibrated with water, with the oil. Allow the charged viscometer to stand in the bath long enough to reach bath temperature.
9.4 Measure the efflux time to the nearest 0.1 s three times and average if the lowest and highest times agree within 0.1 %.
9.5 Clean the viscometer with petroleum spirit followed by acetone and dry with filtered air. Reload the viscometer with oil and measure the efflux time in triplicate. Average if the lowest and highest times agree within 0.1 %.
9.6 If the average times fall within 0.1 %, average the two.
9.7 Using the second calibrated master viscometer, repeat the procedure described in 9.1-9.6 on the same oil.
