Endress+Hauser PROFIBUS Gammapilot M FMG60 Operating Instructions Manual page 61

Gammapilot M FMG 60 - PROFIBUS PA Commissioning
Calibration points for limit detection
A B C
ON ON
OFF
L00-FMG60xxx-05-00-00-xx-002
Calibration points for limit detection; A A A A : Background calibration; B B B B : Covered calibration; C C C C : Free calibration
Background calibration
refers to the following situation:
• The radiation is switched off.
• If possible, the radiation path is completely covered.
The background calibration is necessary, in order to register the natural background radiation at the
mounting position of the Gammapilot M. The pulse rate of this background radiation is
automatically subtracted from any other measured pulse rate. That means: only the part of the pulse
rate which originates from the applied radiation source is taken into account and is displayed.
As opposed to the radiation of the applied source, the background radiation remains nearly constant
during the complete measurement. Therefore, it is not submitted to the automatic decay
compensation of the Gammapilot M.
Covered calibration
refers to the following situation:
• The radiation is switched on.
• If possible, the radiation path is completly covered.
If the radiation path can not be completely covered during the calibration, the covered calibration
can alternatively be performed with the radiation being switched off, which is a way of simulating
complete covering. In this case, the covered calibration is identical to the background calibration.
As the pulse rate of the background radiation is automatically subtracted, the displayed pulse rate is
about 0 c/s.
Free calibration
refers to the following situation:
• The radiation is switched on.
• The radiation path is completely free.
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