Endress+Hauser Gammapilot M FMG60 - Page 70

Commissioning Gammapilot M FMG60 with FOUNDATION Fieldbus
70 Endress+Hauser
Calibration points for limit detection
L00-FMG60xxx-05-00-00-xx-002
Calibration points for limit detection; A: Background calibration; B: Covered calibration; 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 completely covered.
If the radiation path cannot be completely covered during the calibration, the covered calibration
can alternatively be performed with the radiation 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.
!
Note!
This type of simulated calibration is not possible with self-radiating media. In this case it is always
necessary to perform the background calibration and the covered calibration with the radiation path
completely covered.
Free calibration
refers to the following situation:
• The radiation is switched on.
• The radiation path is completely free.
AB
C
OFF
ON
ON