36
6 Set up with the display and adjustment module
MINITRAC 31 • 4 … 20 mA/HART - four-wire
40447-EN-130430
In this menu item you can carry out the adjustment of the sensor.
Caution:
During the first setup or after an instrument reset, the linearization
stands at the preset value pair (90000 ct/s and 0.500 g/cm
3
). These
values are not suitable for your application and must be replaced by
real values. Delete this value pair in the following procedure and carry
out the linearization.
Due to the measuring principle, there is no linear relationship between
pulse rate and density. Hence, this adjustment (i.e. linearization) must
be carried out in any event.
Carry out this adjustment with several points to increase the accuracy
of the measurement.
Note:
Water has as a known density value of 1 g/cm
3
. Carry out the adjust-
ment with water, if possible.
•
Prerequisites:
The radiation is switched on - source container is set to "On"
The tube is completely filled. Possible gas bubbles or air inclusions
can influence the measurement.
The MINITRAC 31 sorts the points automatically according to their
density.
Select "
Show table
" to display and edit the linearization points.
Select "
Linearization - New
" to enter the first point.
Select "
Determine count rate
" to enter the first point.
The determination of the actual count rate lasts 2 minutes. After the
count rate was determined, you can accept the value.
The count rate is stated in ct/s. This is the number of counts per sec-
ond, i.e. the measured radioactive radiation dose actually reaching
the sensor.
Setup/Linearization
