Name/Name Datum/Date Benennung/Designation
Erstellt/Prepared
D.Dornseiff 01/15/98
Index Änderung Name/Name Datum/Date
Service Handbuch HERAcell 150
Service Manual HERAcell 150
C 202613 D.Dornseiff 06/26/03
Dokumentnr./Document No. Seite/Page
Datei/File
50051109_04_EN_C.doc 50051109 / C 45/ 9
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4.14.5 ADJUSTMENTS - IR SENSOR
Calibrating the sensor:
The IR – absorption – sensor is a high precision measurement instrument, therefore,
extreme care must be taken when performing any work on the measurement system.
Due to the non-linear nature of the sensor signal characteristic curve, the effects of an
incorrect zero-point calibration are far greater than is the case with the TCD measuring
cell, which has a linear characteristic curve.
The sensor should be recalibrated whenever the zero-point deviates by more than
+ 0,3 % CO
2
.
All water must be completly removed from the incubator before attempting to
calibrate the sensor, as CO
2
dissolved in water will falsify the measurement re-
sult.
Prior to calibrating the sensor, a reference device must be employed to ensure
that the device setup area is not being artificially enriched with CO
2
as a result of
inadequate ventilation.
Zero-point calibration: CO
2
– controller
1. Remove all water from the device.
2. Select the function level:
Simultaneously press the i; cal and auto-start keys and hold them for 5 sec.
The programm shifts to function level 0.
3. Continue pressing the cal – key and use the arrow keys to select function level 4.
4. Repeatedly press cal – key to select sublevel 3.
Display 0 (on the temperature display)
Display 3 (on the CO
2
– display)
5. Activate the sublevel: Using the arrow keys, set the upper display, 0.
6. Release the keys.
7. The device rests the CO
2
display to 0.
8. Press any key to return to the normal display.
Operating point calibration: CO
2
– controller
After recalibrating the zero-point, you must calibrate the operating point. This proce-
dure is similar to the customer adjustment of the TCD measuring cell.
1. Add CO“ until the gas concentration in the device reches the operating point (e.g.
5%). The actual value must remain stable at 0,1 %. Since the IR sensor does not
indicate the influence of moisture, you need not wait until the humidity in the
chamber has built up.
2. Press the cal – key for 5 sec. All displays flash.
3. Press the % CO
2
key (e.g. 5.0 %)
4. Use the arrow keys to adjust the measured value. (e.g. 5.4)
5. Press the cal – key to acknowledge the value. The display briefly shows cal, fol-
lowed by the correct actual value.
6. Press any key to exit the adjustment routine.
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