Campbell Scientific TGA100 Trace Gas Analyzer Manual - Manual (Page 25)

b) Newer TGAs have a transputer board with a single “D” connector, and a single cable assembly to make this
connection.
5) Connect the 7996 I/O terminal board (if needed) to the optional 7996 I/O board in the TGA PC.
2.3 Routine Operation
Once the TGA100 has been set up, it should be checked periodically to verify proper operation, download data files,
and fill the laser dewar with liquid nitrogen, if necessary. This section gives suggestions for routine operating
procedures.
2.3.1 Startup Procedure
This section describes the routine startup procedure for the TGA100. It assumes the TGA100 has been operational and
is being restarted after a routine shutdown. This section is not intended as a full explanation of the operation of the
TGA100; it is a brief checklist, with cross references to other sections of the manual which provide more detail.
1) Verify the laser dewar vacuum integrity. See section 8.1.
2) Cool the laser dewar. See section 8.1. Do not turn the laser on until it is cold. To run the TGA program with the
laser warm, disable the laser at the main menu before proceeding to the real time screen.
3) If the TGA100 is equipped with the optional liquid nitrogen-cooled detectors (used for long wavelength operation),
cool the detectors with liquid nitrogen. If the TGA100 is equipped with the standard thermoelectric-cooled
detectors, they will be cooled automatically.
4) Start the sample vacuum pump.
5) Turn on the reference gas. A flow rate of approximately 10 ml/min is recommended.
6) Turn on the air gap purge gas, if required (isotope ratio measurements). A flow rate of approximately 10 ml/min is
recommended.
7) Turn on calibration gas supplies, if applicable.
8) Power up the TGA analyzer.
9) Power up the TGA PC, start the TGA program, and start real time operation (see section 3.2).
10) Verify the TGA pressure is consistent with the previous operation of the TGA. The sample pump capacity and the
total flow at the pump determine the pressure. Therefore, if the pressure has changed, it may indicate a problem in
the plumbing.
11) Wait for the laser temperature to stabilize.
12) Verify the correct absorption line is being scanned. See section 0.
13) Initiate the line lock algorithm to bring the absorption line to the center of the spectral scan.
14) For dual ramp applications, start the ramp B line lock.
15) Verify the detector signals are consistent with previous operation of the TGA. If they have changed, check the
operational parameters (see section 4.4.)
16) Verify the reference transmittance at the center of the absorption line is consistent with previous operation of the
TGA. This transmittance is dependent on which absorption line is selected, the concentration in the reference cell,
the pressure in the reference cell, and the laser performance. A significant change indicates a problem.
17) Check the concentration standard deviation to verify proper performance.
The TGA100 is now fully functional. Other features such as Site Means or Gradient Mode, communication with other
devices, or data collection may now be started.
2.3.2 Shutdown Procedure
This section describes the routine shutdown procedure for the TGA100. It assumes the TGA100 is operating in the Real
Time mode.
1) If data collection is on, turn it off.
2) If Site Means or Gradient mode is on, turn it off.
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