Maintenance
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optek-Manual--1004-2003-02--AF45-US-2011-01-04
www.optek.com
9.5 Validation (only for sensor option VB)
The measuring system's functionality can be checked at the installation site
without disassembly, if the sensor is equipped with the option VB validation. For
this check, a reference filter causing an attenuation of the light beam and
simulating absorption inside the measuring gap is inserted into the beam path.
The check is carried out in three steps:
1. Check of the system's zero point
2. Absorption measurement with and without reference filter
3. Evaluation of the results
If the measuring system works correctly, the difference between the measuring
results with and without reference filter corresponds to the validation value given
in the test certificate and on the filter holder.
Check of the system's
zero point
Check the system's zero point, following the instructions given in the instruction
manual of the converter. The system's zero point should be within the range
between 0.000 to +/- 0.004 CU. If the results are too high, the process medium
inside the measuring gap and the windows should be checked for soiling. If the
result is too low, there probably was a contamination at the time of a preceding
zeroing and another zeroing can be carried out instantly.
Always document the zero value before and after the zeroing!
If it is not possible to set the zero point, check the process medium, measuring
segment, windows, lamp module, wiring as well as the serial numbers and
repeat the procedure.
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