Calibration Procedures Model GFC7001E Carbon Dioxide Analyzer
Teledyne Analytical Instruments 198

9.3.3.3. 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 can be found in Section 3.3.4.
When the appropriate contacts are closed for at least 5 seconds, the instrument switches into zero, or span
calibration mode and any internal zero/span valves installed 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 9.4) feature and the
AutoCal attribute “CALIBRATE” is enabled, the GFC 7001E/EM will not recalibrate the analyzer until 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.
9.4. AUTOMATIC ZERO/SPAN CAL/CHECK (AUTOCAL)
The AutoCal system allows unattended periodic operation of the ZERO/SPAN valve options by using the GFC
7001E/EM Analyzer’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 Se quence 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 Caus es the Sequence to perform a Span concentration calibration/check only.