Brookfield RST Rheometer - Manual (Page 56)

Brookfield Engineering Labs., Inc. page 56 Manual No. M14-223
Appendix C Calibration Check
The calibration check procedure is performed in order to verify that your RST Rheometer is making correct
viscosity measurements. It can be done in standalone mode or under control of Rheo-3000 software
running on a PC. Perform the calibration check with the spindle that is most frequently used with your
instrument. You do not need to perform a calibration check with additional spindles unless there is a
concern that a specific spindle is not measuring properly.
The calibration check can be performed at regularly scheduled time intervals determined by you (before
each shift, weekly, monthly, etc) or at any time when there is concern that the instrument is not measuring
correctly.
Before performing the calibration check, it is advisable to perform the Zeroing procedure. This feature is
accessed in the Settings menu in standalone mode. At a minimum run both the High Range and Low
Range Zeroing procedures. The time required to do both is slightly more than a half hour.
Use the appropriate viscosity standard for the spindle that you want to test. Consult the following table
which shows the fluid that is recommended for each type of spindle and the required sample volume to
perform the calibration check:
Cone Spindles Fluid Sample Volume
RCT-25-1 B41000 0.1mL
RCT-25-2 B73000 0.2mL
RCT-50-1 B10200 1.0mL
RCT-50-2 B21000 2.0mL
RCT-75-1 B4900 2.5mL
RCT-75-2 B10200 5.0mL
Coaxial Spindles Fluid Sample Volume
CCT-8 B41000 1.0mL
CCT-14 B10200 3.4mL
CCT-25 16.8mL 16.8mL
CCT-40 B2000 68.5mL
CCT-DG B200 15.7mL
If you have an RST-SST Rheometer and use vane spindles, Brookfield recommends that you perform a
calibration check with any one of the coaxial spindles chamber geometries which will also attach to your
instrument.
Use a circulating temperature bath to condition the viscosity standard to a set temperature, normally 25°C.
All Brookfield viscosity standards are calibrated at 25°C. Additional temperature calibrations are available
upon request when the fluid is ordered from Brookfield or an authorized dealer. Brookfield also supplies a
selection of TC series Temperature Baths for this purpose.
If you have an RST-CPS Rheometer with Peltier Temperature control, you do not require the circulating
temperature bath. Temperature control capability is built into the plate on the instrument.
Prepare the proper sample volume for the test and condition to the defined temperature within +/- 0.1°C.
Mineral oil is highly temperature sensitive, so it is important to do this correctly. If using the RST-CPS
Rheometer, trim the sample around the circumference of the cone spindle.
The calibration check procedure is performed at 3 separate controlled torque values: 125, 250 and 375
per mille. The spindle rotates for at least one minute at each torque value. The viscosity reading at each
torque value is recorded. The three viscosity readings must each be within +/- 3% of the actual fluid value
for the calibration check to pass.