Cannon Instrument CMRV-5000 - Manual (Page 37)

31
CANNON ® Mini-Rotary Viscometer CMRV-5000 Instruction & Operation Manual
Version 1.0b—August, 2011; CANNON ® Instrument Company
2139 High Tech Road • State College, PA • 16803 • USA
CHAPTER
7
CALIBRATING THE CMRV
TEMPERATURE PROBE
The CMRV temperature probe must be calibrated before performing the
initial cell calibration or running temperature profiles. A complete
calibration session involves setting temperature offsets in the VISCPRO
software for key temperature checkpoints beginning at 80°C, then 50°C,
then other temperatures at 5-degree increments from 0 to -40°C. The
calibration process ensures that temperature probe readings are correctly
interpreted by the CMRV hardware and software. This ensures accurate
temperature control throughout the temperature profile.
There is a 10-minute equilibration time at each calibration temperature.
The entire probe calibration procedure requires at least 3 hours and
requires operator input at each temperature plateau. Thereafter, the probe
should be calibrated at the user's discretion, particularly when viscosity
data is suspect, the instrument exhibits poor repeatability, or the probe
temperature on the display does not correspond with the calibrated
thermometer reading.
The CMRV temperature probe calibration and cell calibration proce-
dures should both be completed shortly after initial installation of the
CMRV software. Probe calibration must precede cell calibration to
ensure accurate temperature control during the cell calibration process.
Periodic probe calibration will enhance the accuracy of test results.
Probe calibration procedure
1. After preparing the CMRV instrument (see Chapter 6), place 10 ml
± 0.1 ml of any clean generic oil sample into each of the viscometric
cells being calibrated. Carefully place the rotors into their corre-
sponding viscometric cells and secure each rotor in position with the
rotor pin.
Checking temperature probe
2. Make sure that the thermistor probe sheath is securely seated in the
cylindrical opening on the right side panel of the CMRV housing,
and that the LEMO plug is inserted in the Temp Probe connection on
the CMRV-5000 rear panel..
3. Using the VISCPRO ® software, click Service/MRV/Temperature
Probe Calibration. The Temperature Probe Calibration window
will open (see graphic, next page).
NOTE In preparation for the heating phase of the calibration procedure, remove
the calibrated -46°C to +30°C thermometer from the CMRV block to
prevent separation of the mercury column. Reinsert the calibrated
thermometer when CMRV block temperature is within its range.