Cannon Instrument miniAV-LT - Manual (Page 62)

CANNON ® miniAV-LT Automatic Viscometer with VISCPRO ® Instruction & Operation Manual
Version 1.a— May, 2009; CANNON ® Instrument Company
2139 High Tech Road • State College, PA 16803 • USA
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Maximum tube empty time %: Adjust this setting to select the percentage of the drop time between the
bottom sensor and the sensor at the top of bulb 1. The default value is
100%.
Pull Sample Pulse On Time Adjust this setting to help eliminate bubbles that can occasionally be
formed as the vacuum draws some types of samples into the viscometer
tube. The pulse value is a percentage of time that the sample will be
drawn up into the tube during each five-second interval of the draw
period. A setting of 100% (default setting) will not pulse the sample. A
setting of 20 would pull the sample for one second in each five-second
interval. Sample pulsing should only be used if it is found to alleviate
bubbling during the sample draw period.
Bulb overdraw Use the Bulb Overdraw button/window to set the amount of time in
seconds that the instrument will draw sample AFTER the sample menis-
cus has covered the target sensor in the viscometer tube. More viscous
materials may require a larger overdraw time to ensure that the sample
meniscus does not dip below the target sensor during temperature equili-
bration.
Proper adjustment of the overdraw can maximize efficiency of the test
cycle. Too much overdraw can contaminate vacuum lines and interfere
with pump operation. Too little overdraw can interfere with the initiation
of sample testing following the temperature equilibration period. Note
that lighter oils will be pulled higher in the bulb.
Calibration
The Calibration window provides controls for calibrating each bulb
associated with your instrument. You may need to log onto the system as
a Manager to access these security-protected calibration functions.
Use the bulb spin controls to display current constants and valid
check standard data available for calibration of each bulb.
Calibration constants are determined individually for each bulb. Data for
automatic calculation of tube calibration constants is derived from check
standards run using that tube.
For information regarding the miniAV-LT calibration procedure, see
Chapter 3, Calibrating the miniAV-LT.
The Calibration window options are described briefly below: