Teledyne 2020 - Explosion proof thermal conductivity analyzer - Manual (Page 49)

Thermal Conductivity Analyzer Operation 4
4-15 Teledyne Analytical Instruments
4.4.1.3 Cell Failure
Cell failure in the 2020 is usually associated with inability to zero the
instrument with a reasonable voltage differential across the Wheatstone
bridge. If this should ever happen, the 2020 system alarm trips, and the
VFD 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.
c. Check flowmeter to ensure that the flow is no more than
200SCCM
d. Check temperature controller board.
e. Check gas temperature.
If none of the above as indicated, the sensor may need to be replaced.
Check warranty, and contact Analytical Instruments Customer Service.
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. Scroll SPAN
and enter the span function. The screen that appears allows you to select
whether the span calibration is to be performed automatically or manually.