Teledyne 2000A-EU - General purpose thermal conductivity analyzer - Manual (Page 52)

4 Operation Model 2000A-EU
4-14 Teledyne Analytical Instruments
Generally, you have a good zero when
Slope is less than 0.05 ppm/s for
about 30 seconds.
Once zero settling completes, the information is stored in the analyzer’s
memory, and the instrument automatically returns to the Analyze mode.
4.4.1.3 Cell Failure
Cell failure in the 2000 is usually associated with inability to zero the
instrument with a reasonable voltage differential across the Wheatstone bridge. If
this should ever happen, the 2000 system alarm trips, and the LCD displays a
failure message.
CELL CANNOT BE BALANCED
CHECK YOUR ZERO GAS
Before replacing the sensor:
a. Check your zero gas to make sure it is within specifications.
b. Check for leaks downstream from the sensor, where contamina-
tion may be leaking into the system.
If there are no leaks and the zero gas is OK, the sensor may need to be
replaced. Check warranty, and contact Analytical Instruments Customer Ser-
vice.
4.4.2 Span Cal
The Span button on the front panel is used to span calibrate the analyzer.
Span calibration can be performed in either the automatic or manual mode.
CAUTION: If you are spanning the Cal Range by itself (multiple
application analyzers only), use manual mode
zeroing.
If you want to calibrate ALL of the ranges at once
(multiple application analyzers only), use
auto mode
spanning in the Cal Range.
Make sure the span gas is flowing to the instrument.
4.4.2.1 Auto Mode Spanning
Observe all precautions in sections 4.4 and 4.4.2, above. Press Span to
enter the span function. The screen that appears allows you to select whether the
span calibration is to be performed automatically or manually. Use the
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