Endress+Hauser Gammapilot M FMG60, Руководство по эксплуатации

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Commissioning Gammapilot M FMG60 PROFIBUS PA
70 Hauser
6.5 Calibration for density and concentration
measurements
6.5.1 Basic principles
The calibration points for the measurement are entered in the "calibration" (*1) function
group. Each calibration point consists of a density value and the associated pulse rate.
Calibration points for density and concentration measurements
Function of the calibration points
For density and concentration measurements the Gammapilot M needs (apart from the
length of the irradiated measuring path) the following two parameters:
• The absorption coefficient  of the material measured
• The reference pulse rate I
0
6)
.
It calculates these parameters automatically from the following calibration points:
• Background calibration (calibration with the radiation switched off)
• Up to nine calibration points for samples of various known densities.
NOTICE
With self-radiating media it is always necessary to perform the background calibration
with a filled pipe. A simulated calibration with an empty pipe is not possible in this
case.
A0018128
0 Background calibration
1-9 Calibration points for various densities
Two-point calibration
The recommended comparisen procedure for high exactness standards about the whole
measuring range is the two-point calibration. First the background calibration occurs. The
two calibration points will be adapt. They should lie differ considerably. After input of both
calibration points, the Gammapilot M calculates the parameters I
0
und

.
One-point calibration
If a two-point calibration is not possible, a one-point calibration can be carried out.
That means, that apart from the background calibration only one further calibration point is
used. This calibration point should be located as near as possible to the operating point.
Densities in the proximity of this operating point are measured fairly precisely, whereas the
precision may decrease with increasing distance to the operating point.
In one-point calibration, the Gammapilot M only calculates the reference pulse rate I
0
.
For the absorption coefficient it uses the standard value

= 7.7 mm
2
/g in this instance.
6) I
0
is the pulse rate for the tube being empty. The value is significantly higher than any real pulse rate occurring during the measurement.
O FF ON
0 1
9