Diagnostics and troubleshooting Gammapilot FMG50
90 Endress+Hauser
8.6.7 Gammagraphy limit parameter
Gammagraphy radiation is detected if the pulse rate at the detector exceeds the maximum
gammagraphy limit value. This value is determined using the maximum pulse rate from
the calibration (generally "upper range value") and the configured gammagraphy
sensitivity.
8.6.8 Gammagraphy sensitivity parameter
The suitable sensitivity value largely depends on the process and ambient conditions.
Therefore no general rules apply for the choice of sensitivity value. However, the following
principles can serve as a guide:
• A small value (between 1 and 3) should be entered for homogeneous products with an
even, calm surface. Gammagraphy is then detected with a high degree of sensitivity.
• A large value (between 3 and 7) should be entered for non-homogeneous products and
turbulent surfaces, as random variations in the pulse rate would otherwise be wrongly
detected as a gammagraphy event.
If the device occasionally reports gammagraphy even though no gammagraphy
radiation is present, then it advisable to increase the value slightly. Conversely, the
value should be reduced if gammagraphy radiation was not detected.
8.7 Density recalibration for multi-point calibration
8.7.1 General principles
A recalibration of the measurement can be necessary if the measuring conditions have
changed, e.g. in the event of deposit buildup on the pipe.
The absorption coefficient µ of the original calibration is maintained but the reference
pulse rate I
0
is redetermined, which causes a shift in the overall linearization function.
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25 Linearization shift
I Pulse rate (pulses per second, cnt/s)
ρ Density
8.7.2 Performing density recalibration for multi-point calibration
1. In the operating menu, change the type of calibration from Multipoint calibration
option to One point calibration option
Application → Sensor → Density Settings → Calibration or Linearization type
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