Gammapilot M FMG60 PROFIBUS PA
Commissioning
Hauser
61
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
A0018111
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.
NOTICE
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%.
C
B
A
O
FF
ON
ON
