Siemens SITRANS LG270 Operating Instructions Manual page 59

Step 3
Adjustment
Step 4
Linearization
PBD-51041066
Interface measurement: If you select "Interface", the instrument needs
more information, such as the distance to the interface, the dielectric
constant of the upper medium or whether or not there is a superim-
posed gas phase.
Demonstration mode: This mode is only suitable for test and demon-
stration purposes. In this mode, the sensor ignores all parameters
and reacts immediately to all measured value changes within the
measuring range.
Application - Level measurement
The level measurement refers to the product surface which is the limit
to the gas phase.
As a standard feature, the instrument is set to level measurement of
liquids. You can switch over the instrument to the measurement of
bulk solids.
•
Liquids
– Solvents, oils, LPG - dielectric constant < 3
– Chemical mixtures - dielectric constant 3 ... 10
– Water-based - dielectric constant > 10
•
Bulk solids
– Dusts, wood chips - dielectric constant < 1.5
– Granules, dusts, powders - dielectric constant 1.5 ... 3
– Cereals, flour - dielectric constant > 3
Application - Interface measurement
The interface measurement refers to the phase limit between two
liquids. The total level is also available as a measured value.
•
Superimposed gas phase present
– Check if there is a superimposed gas phase in the vessel. This
is always the case if the total level never touches the process
fitting.
•
Properties
– Here you can enter the dielectric constant of the upper medium
– As an alternative you can enter the distance to the interface
Adjustment for the level measurement
If you have selected level measurement in the previous menu, then
you can enter the values for the min. and max. adjustment. The value
to be entered refers to the distance from the sealing surface of the
process fitting (sensor reference plane) to the surface of the product.
Adjustment for the level and interface measurement
If you have selected interface measurement in the previous menu,
then you can enter the values for the min. and max. adjustment of
level and interface or accept the values of the level measurement. The
entered value refers to the distance from the sealing surface of the
process fitting (sensor reference plane) to the total level or interface.
Linearization is required if the measured value should be outputted
in proportion to the volume and not the level. The linearization acts
SITRANS LG270 - Operating Instructions 59