ASTM D6616 Standard Test Method for Measuring Viscosity at High Shear Rate by Tapered Bearing Simulator Viscometer at 100°C
13. Analysis of Sample Oils - Obtaining Torque Values
13.1 Inject 50 mL of each test oil slowly (~1 min) into the fill tube, wait for temperature/torque equilibrium, then apply the bouncer button (see Note 21), and record the torque value after it again stabilizes.
13.1.1 If the amount of test oil is limited, a different injection procedure may be used. Fill the syringe with 30 mL of oil and make three injections of10 mL each and waiting 10 s between injections.
NOTE 23 - If the amount of test oil is severely limited, contact the manufacturer regarding a technique requiring no more than 10 to 15 mL of test oil.
14. Calculation of Viscosity
14.1 Calculate the viscosity of the test oil to the nearest 0.01 mPa·s by inserting the value of torque obtained in Eq 1 and using the constant values determined for mv and bv.
14.2 After every set of six sample oil analyses, analyze NNR-10.
14.2.1 If the viscosity value is within 2 % of the value on the container, proceed to 14.3.
14.2.2 Ifthe viscosity value of NNR-10 differs by more than 2 % from the value on the container, inject reference oil R-2400 and recheck the NNR-10/R-2400 torque ratio as in 12.6.2. If necessary use these most recent torque values to recalibrate using 12.3 through 12.5.
14.3 Continue the sample analyses until completed according to the sequence of Section 13.
15. Maintenance of Instrument Precision
15.1 Intermittent Use - If the TBS viscometer is not to be used for more than 1/2 h, inject 25 mL of idling oil into the cell. The idling oil may be left in the operating rotor/stator cell for a week or more, if required. Periodically (every seven to ten days), re-inject idling oil.
NOTE 24 - A test oil or reference oil should not be left in the gap for more than 15 to 20 min since deposits from the oil may be laid down, and modify the very small rotor/stator gap.
15.2 Standby Procedure - When testing is complete, inject idling oil to flush the rotor/stator cell. Leave the rotor at operating position in preparation for the next use. Inject idling oil about once a week while on standby.
15.3 Shutdown Procedure - Inject idling oil and raise rotor (see Note 12) 0.5 mm to its shutdown storage position. Press bouncer button or hold turntable ball contact away from load-cell platen and shut off motor. Then shut off main console power.
15.3.1 When starting up again, see 9.2 or 9.3.
15.4 Cleaning Rotor/Stator Cell:
NOTE 25 - Continuous operation of the TBS viscometer without a periodic flush with a polar organic solvent such as dimethyl sulfoxide will eventually lead to a test cell whose surfaces are coated with deposits from the oils being analyzed. It is recommended that the test cell be treated with an organic polar solvent after every 200 to 300 analyses if used continuously and after every 50 to 70 analyses if used intermittently.
15.4.1 After a routine shutdown in accordance with 15.3 and after the test cell has cooled to room temperature, fill the test cell with the polar organic solvent.
15.4.2 Lower the rotor (see Note 12) 0.3 mm from its shutdown storage position of 0.5 mm above the rotor operating position (see 11.3.1 and Note 19).
15.4.3 While pressing bouncer button (or holding turntable ball away from platen by lightly pressing the brass pin on the motor turntable in a clockwise direction), turn on console's main power and motor switches. When motor is running, release restraint to free motion of the turntable.
15.4.4 After 10 min of operation with the polar solvent, purge the polar solvent from the cell with idling oil using a 60 mL stepwise injection of one 30 mL injection followed by two 15 mL injections, all spaced about 5 min apart.
15.4.5 Either start up the TBS viscometer and recalibrate (see 9.3) or shut the instrument down following the directives of 15.3.
