Part No: 4417341 Revision 10
Installation Manual 18
954 SmartServo FlexLine
3.1.1. Level Measurement
A level variation of product, in which the displacer is partially immersed, causes a change
in buoyancy, which will be detected by the force transducer. The resulting difference
between measured and desired value will cause a variation in the position of the stepper
motor and consequently raise or lower the position of the displacer until the measured
value equals the desired value.
To avoid oscillations, a certain hysteresis and integration time is software adjustable. This
results in a stable and accurate averaged level measurement.
The stepper motor turns one revolution for every 10 mm of vertical movement of the
displacer.
One revolution is divided into 200 steps, therefore one step is equivalent to 0.05 mm. This
resolution is a direct consequence of the stepper motor principle. The correct functioning
of the stepper motor is continuously checked. This is achieved by decoding the unique
pattern of an encoder disk mounted on the motor shaft.
3.1.2. Interface between two Products
Measurement of the interface between two products is achieved by sending an interface
command to the gauge. This causes the stepper motor processor to move the displacer to
a position where the apparent weight of the displacer matches a pre-programmed set
point.
3.1.3. Relative Density
To measure the relative density, the displacer is positioned at specific heights and the
apparent weight of the displacer at each height is measured. Knowing the volume of the
displacer, its weight in air, and the measured apparent weight, the relative density of the
product at each position of the displacer can be calculated. The software for the density
measurement is available as an option.