E C O P H Y S I C S Calibration
CLD 780 TR / July 2000 85
3. Check the calibration gas stability:
– Supply the analyzer with calibration gas of known concentration at
cal. gas inlet.
– Push ”TEST“ key
– Select ”Counts“
– Under ”Chan“ (channels) select ”All“ and under ”Int[s]“ (integrati-
on time) enter the desired time interval.
Now raw data values in ”Counts/second“ are displayed on a continu-
ous basis for the NO, zero and NO.c signals. The stable values for
NO and NO.c should now be compared with the values that were ob-
tained under the same conditions when the analyzer was new.
As soon as the raw values agree approximately with the selected NO-
calibration concentration, the single point calibration can be started. If
significant deviation from the expected values occur, the reason why
must be investigated.
Possible causes are:
– wrong calibration gas concentration was entered as ref. gas
concentration
– dirty reaction chamber (or red filter)
– leaky gas lines
– Return with ”MEAS“.
4. Calibration:
The operator is led through the calibration procedure in a simple dia-
log fashion. More details are presented in paragraph 5.2.2.7.1.
5. Copying of calibration value into other ranges:
After accepting the calibration the ”Copy Cal“-window appears. Co-
pying the calibration to the displayed range can either be accepted
(with ”YES“) or refused (with ”NO“).
Caution: If the analyzer is being operated in the ”NO and NO
2
“
mode, ”Select Instrument“ will appear on the display after pushing the
”CAL“ key. In this case ”CLD 780 TR“ has to be chosen. After that the
calibration follows the same procedure as described in 5.2.2.7.1.
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