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T400 Ozone Analyzer Operator’s Manual Troubleshooting & Service
257
Once the instrument passes a leak check, do a flow check (see Section 11.3.6) to
make sure adequate sample is being delivered to the optical bench assembly.
Confirm the sample pressure, sample temperature, and sample flow readings are
correct and have steady readings.
Verify that the sample filter element is clean and does not need to be replaced.
12.5.3. INABILITY TO SPAN – NO SPAN BUTTON (CALS)
Confirm that the O
3
span gas source is accurate. This can be done by
inter-comparing the source with another calibrated monitor, or having the O
3
source
verified by an independent traceable photometer.
Check for leaks in the pneumatic systems as described in Section 11.3.4.
Make
sure that the expected span gas concentration entered into the instrument
during calibration is not too different from expected span value.
Check to make sure that there is no ambient air or zero air leaking into span gas
line.
12.5.4. INABILITY TO ZERO – NO ZERO BUTTON (CALZ)
Confirm that there is a good source of zero air. If the IZS option is installed,
compare the zero reading from the IZS zero air source to the calibration zero air
source.
Check for leaks in the pneumatic systems as described in Section 11.3.4.
Che
ck to make sure that there is no ambient air leaking into zero air line.
12.6. OTHER PERFORMANCE PROBLEMS
Dynamic problems (i.e. problems that only manifest themselves when the analyzer is
monitoring sample gas) can be the most difficult and time consuming to isolate and
resolve. The following section provides an itemized list of the most common dynamic
problems with recommended troubleshooting checks and corrective actions.
12.6.1. TEMPERATURE PROBLEMS
Individual control loops are used to maintain the set point of the UV Lamp, IZS Ozone
Generator (Optional) and Metal Wool Scrubber (Optional) temperatures. If any of these
temperatures are out of range or are poorly controlled, the T400 will perform poorly.
12.6.1.1. Box Temperature
The box temperature sensor is mounted to the Motherboard and cannot be disconnected
to check its resistance. Rather check the BOX TEMP signal using the SIGNAL I/O
function under the DIAG Menu (see Section 12.1.2).
This parameter will vary with ambient temperature, but at ~30
o
C (6-7 above room
temperature) the signal should be ~1450 mV.
06870C DCN6332