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BA_078 Rev 1F6 Level transmitter PASCAL Ci4 LEVEL
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6.1.2
Tank shape
The fill height is converted to a fill volume
using the tank shape table.
The table is stored in the device as a series
of fill height/fill volume pairs. The tank
shape table can therefore be easily deter-
mined from the tank documentation. A con-
version into percent or the like is not neces-
sary.
It is also possible to teach in the tank shape
to depict complex geometries in the tank
shape table such as agitators, for example
(see 6.5.3.4).
fill height
fill volume
h
V
V
h
0
0
Figure 8: Calculating the fill volume using the tank
shape table
The control points of the tank shape table are entered and stored as height/volume pairs.
This means that a change in density does not affect the tank shape definition.
The table is managed internally in metre/litre pairs and converted for the display depend-
ing on the units selected. The display therefore adapts accordingly to the table when con-
verting the height and volume unit.
6.1.3
Scaling the current output
Each of the level variables (height, volume, weight) - as well as the measured pressure for
calibration purposes - can be issued at the current output. The scaling is done by indicat-
ing a measured value at 4 mA (lower range value) and a value at 20 mA (upper range val-
ue). The limit values are entered in its unit depending on the output variable selected.
These values, like all level variables, relate to the level zero.
The scaling of the measurand (height, volume, weight, pressure) are independent of each
other. A separate pair of values at 4 and 20 mA are stored in the device for each meas-
ured variable.
h=0
pressure
zero
level
zero
fill height
height
offset
p=0
fill height at
20 mA
fill height at
4 mA
h
20mA
h
4mA
Figure 9: Scaling the current output