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Model 9110TH NOx Analyzer Calibration Procedures
Teledyne Analytical Instruments 213
9.4.3.3. Use of Zero/Span Valve with Remote Contact Closure
Contact closures for controlling calibration and calibration checks are located on the rear panel
CONTROL IN connector. Instructions for setup and use of these contacts are found in Section 3.3.1.6.
When the contacts are closed for at least 5 seconds, the instrument switches into zero, low span or high
span mode and the internal zero/span valves will be automatically switched to the appropriate
configuration.
The remote calibration contact closures may be activated in any order.
It is recommended that contact closures remain closed for at least 10 minutes to establish a reliable
reading.
The instrument will stay in the selected mode for as long as the contacts remain closed.
If contact closures are being used in conjunction with the analyzer’s AutoCal (see Section 9.5) feature
and the AutoCal attribute “CALIBRATE” is enabled, the 9110T will not re-calibrate the analyzer
UNTIL when the contact is opened. At this point, the new calibration values will be recorded before the
instrument returns to SAMPLE mode.
If the AutoCal attribute “CALIBRATE” is disabled, the instrument will return to SAMPLE mode,
leaving the instrument’s internal calibration variables unchanged.
9.5. AUTOMATIC ZERO/SPAN CAL/CHECK (AUTOCAL)
The AutoCal system allows unattended periodic operation of the ZERO/SPAN valve options by using
the 9110T’s internal time of day clock. AutoCal operates by executing SEQUENCES programmed by
the user to initiate the various calibration modes of the analyzer and open and close valves appropriately.
It is possible to program and run up to three separate sequences (SEQ1, SEQ2 and SEQ3). Each
sequence can operate in one of three modes, or be disabled.
Table 9-2: AUTOCAL Modes
MODE NAME ACTION
DISABLED
Disables the Sequence.
ZERO
Causes the Sequence to perform a Zero calibration/check.
ZERO-SPAN
Causes the Sequence to perform a Zero point
calibration/check followed by a Span point
calibration/check.
SPAN
Causes the Sequence to perform a Span concentration
calibration/check only.