Cannon Instrument CAV-2000 - Manual (Page 77)

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CANNON ® Automatic Viscometer Models CAV-2100 and CAV-2200 with VISCPRO ® Instruction & Operation Manual
Version 2g — May, 2009; CANNON ® Instrument Company
2139 High Tech Road • State College, PA 16803 • USA
Procedure
1. Disconnect the waste can from the drain tube(s).
CAUTION Be careful when handling the drain tube, to avoid spilling or splashing
waste solvent collected in the tube.
2. Pour the collected solvent out of the waste can into a proper waste
storage container.
3. Replace the drain tube(s) in the waste can.
WARNING Waste solvents can present possible environmental and health hazards.
Dispose of all waste solvents according to environmental safety regula-
tions.
Waste can connections
For information regarding waste can connections, refer to the CAV
Installation & Setup Guide.
Viscometer tubes
The CAV is equipped with borosilicate glass capillary viscometer tubes
having a wide viscosity range. The upper viscosity limit is up to 100
times the lower viscosity limit, depending on the tube type. Each viscom-
eter tube contains four glass-bead thermistors used for sensing the level
of the sample within the tube (fast-run viscometer tubes contain three
glass-bead thermistors). There are two viscometer tubes installed in each
CAV-2100 temperature bath; one viscometer tube is installed in each
CAV-2200 temperature bath.
Tube thermistors
The glass-bead thermistor is a precision sensor embedded in the viscom-
eter tube. The sensor heats up slightly when an electrical current is
passed through it. When the thermistor is covered by a sample, the
sample draws heat away from the thermistor, thereby cooling it. As the
sample meniscus passes the thermistor, the thermistor quickly returns to
its “hot” state. The sensor board detects this change in thermistor tem-
perature and records the time accurately to within one-hundredth (0.01)
of a second.
Timing bulb determination
As the sample is drawn into the viscometer tube, the VISCPRO ® software
automatically determines which timing bulb will be used to test the
sample.
The sample will be drawn into the bulb above the upper timing thermistor.
That bulb will serve as the overflow bulb for that particular test run.