Gammapilot M FMG60 with FOUNDATION Fieldbus Commissioning
Endress+Hauser 69
6.4 Calibration for level measurement and limit detection
6.4.1 Basic principles
The calibration points for the measurement are entered in the "calibration" (*1) function group.
Each calibration point consists of a level and the associated pulse rate.
Calibration points for level measurement
L00-FMG60xxx-05-00-00-xx-001
Calibration points for level measurement; A: Background calibration; B: Full calibration; C: Empty calibration
Background calibration
refers to the following situation:
• The radiation is switched off.
• Within the measuring range, the vessel is filled as far as possible (ideally: 100%).
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.
Full calibration
refers to the following situation:
• The radiation is switched on.
• Within the measuring range, the vessel is filled as far as possible (ideally: 100%, minimum 60%).
If the vessel cannot be filled to at least 60% during the calibration, the full calibration can
alternatively be performed with the radiation switched off, which is a way of simulating a filling of
100%. In this case, the full 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 cps.
!
Note!
This type of simulated calibration is not possible with self-radiating media. In this case it is always
necessary to perform the background and full calibration with the vessel filled to 100%.
Empty calibration
refers to the following situation:
• The radiation is switched on.
• Within the measuring range, the vessel is emptied as far as possible (ideally: 0%, maximum 40%).
C
B
A
OFF
ON
ON
To Next Page
Loading...
