Endress+Hauser Gammapilot FMG50 - Page 60

Commissioning Gammapilot FMG50
60 Endress+Hauser
The Gammapilot FMG50 requires the following parameters for density and concentration
measurements:
• The length of the irradiated measuring path
• The absorption coefficient µ of the medium
• The reference pulse rate I
0
Two types of calibration are available to determine these parameters:
• Multi-point calibration
• One-point calibration
Multi-point calibration
Multi-point calibration is recommended particularly for measurements in a large density
range or for particularly accurate measurements. Up to 4 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.
I
r
I
max
I
min
r
max
min
r
A0042200
I Pulse rate
ρ Density
Once the calibration points have been entered, the Gammapilot FMG50 calculates the
reference pulse rate I
0
and the absorption coefficient µ parameters on its own.
One-point calibration
A one-point calibration can be performed if a multi-point calibration is not possible. This
means that apart from the background calibration only one additional calibration point is
used. This calibration point should be as close as possible to the operating point. Density
values near this calibration point are measured quite accurately, but the accuracy can
decrease as the distance from the calibration point increases.
I
r
A0042199
I Pulse rate
ρ Density
In one-point calibration, the Gammapilot FMG50 only calculates the reference pulse rate
I
0
. For the absorption coefficient µ, the device uses a predefined value. This predefined
value can be edited directly or an absorption coefficient for the specific measuring point
can be determined using the Applicator. The default value for the absorption coefficient is
µ = 7.7 mm
2
/g.