4.4
»Dry calibration« for open vessels (Deltapilot)
It may not always be possible to fill and empty the vessel for the calibrations as described
in Sections 4.2 and 4.3. To cover this eventuality the Silometer FMX 570 can be calibrated
»dry« by using the sensor constants. For this alternative calibration you need:
•
the »zero frequency« and »sensitivity« of the sensors,
•
the »empty« level or offset at which the measurement should start
•
the maximum height of the liquid column and
•
the density of the liquid.
Caution!
•
Check the calibration during the first filling of the tank! If your calculations are
incorrect the levels measured will be incorrect also!
Sensor constants f
o
,
∆
f
V3H5/V3H6
The sensor constants »f
o
« and »
∆
f«, see Section 2.1, are to be found in Table 2.2 on
page 9. For the theoretical calibration, however, it is recommended that the zero
frequency of the installed Deltapilot S at atmospheric pressure is read from V0H8.
Step
Matrix
Entry
Significance
1
V3H5
e.g. 99.5
Enter »f
o
« value (read from V0H8)
2
-
»E«
Register entry
3
V3H6
e.g. 1.02
Enter »
∆
f« value
4
-
»E«
Register entry
Note!
•
The zero frequency of the sensor is in fact dependent upon the sensor orientation,
so that there may be a slight difference between the value read from Table 2.2 and
that of the factory calibration which is printed in the sensor housing. This effect is
compensated during the standard calibration, where the factory values are used.
VH
0 0
VH
0 0
2000
50
BA119Y61
Sensitivity V3H2
measurement span
display span
Offset V3H1
P =
ρ
x g x
∆
h
Empty, e.g. 50 hl
M
a
x.
l
e
vel
e.g. 10
m
= 980.
7 m
b
ar
Max. display, e.g. 2000 hl
Fig. 4.3:
Parameters for dry calibration
with Deltapilot probes
Silometer FMX 570
Chapter 4: Calibration and Operation
20
