Endress+Hauser Gammapilot M FMG60 FOUNDATION Fieldbus, Руководство по эксплуатации

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Commissioning Gammapilot M FMG60 FOUNDATION Fieldbus
74 Hauser
the Gammapilot M only calculates the reference pulse rate I
0
. In this case, it uses the
default value µ = 7.7 mm 2 /g for the absorption coefficient.
Multiple-point calibration
Multiple-point calibration is recommended particularly for measurements in a large
density range or for particularly accurate measurements. Up to 9 calibration points can be
used over the entire measuring range. The calibration points should be as far apart as
possible and should be evenly distributed over the entire measuring range. Once the
calibration points have been entered, the Gammapilot M calculates the I
0
and µ
parameters on its own. Multiple-point calibration is recommended particularly for
measurements in a large density range or for particularly accurate measurements.
Recalibration
The Gammapilot M provides an additional calibration point (calibration point "10") for
recalibration. This point can be entered if the measuring conditions have changed, e.g. as a
result of deposit buildup in the measuring tube. Once the calibration point has been
entered, I
0
is recalculated according to the current measuring conditions. The absorption
coefficient µ from the original calibration remains unchanged.
Methods for entering the calibration points
Automatic calibration
In the case of automatic calibration, the calibration point in question is implemented on
the vessel or the measuring tube, i.e. the measuring tube is filled with a medium of the
desired density. The radiation remains switched off for background calibration, while
radiation is switched on for all other calibration points. The Gammapilot M records the
pulse rate automatically. The associated density is determined in the laboratory and
entered by the user.
Manual calibration
In order to achieve a high level of measuring accuracy, it is advisable to determine the
pulse rates for several samples at a constant density and to calculate the average density
and average pulse rate for these samples. These values can then be entered manually in
the Gammapilot M. If possible, this procedure should be repeated at another density. The
two density values should be as far apart as possible.
The calibration date is not set automatically during manual calibration. It must be
entered by the user in the "Calibration date" (*C7) function.
7.5.2 Background calibration
Excerpt from the operating menu
The following excerpt from the operating menu illustrates the entries to be made for
background calibration. The individual functions are explained in detail in the sections that
follow.
*10
backgr. calibr.
0: stop/ edit
1: start *11
avg. pulse rate *12
bgr. pulse rate
-1: not calibrated
0
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A0037161-EN