Page 6 Instruction Manual, Alfa Laval Potentiometric Level Transmitter
TE91K021-EN5
3. General Description
3.1 Working principle of the potentiometric level transmitter
3.3 Recycling information:
Unpacking
Packing material consists of plastic and cardboard boxes.
Cardboard boxes can be reused, recycled or used for energy recovery.
Plastics should be recycled or burnt at a licensed waste incineration plant.
Maintenance
During maintenance seals and O-ring should be replaced (only on clamp connections).
All metal parts should be sent for material recycling.
Worn out or defective electronic parts should be sent to a licensed handler for material recycling.
Oil and all non metal wear parts must be taken care of in agreement with local regulations.
Scrapping
At end of use, the equipment shall be recycled according to relevant, local regulations. Beside the equipment
itself, any hazardous residues from the process liquid must be considered and dealt with in a proper manner.
When in doubt, or in the absence of local regulations, please contact the local Alfa Laval sales company.
3.3 General description
The liquid is stored in a ground connected tank.
The immersed level probe is a low resistance rod where the ends are powered by an AC
generator operating in the lower kilohertz frequency range. Between the rod and the tank wall
is an endless amount of high level resistances. Since they connect to the same potential (the
tank wall) they can be shown as two equivalent resistances, R1 and R2 connected to an im-
aginary center point. A high resistance input amplifier is connected between the generator
and the tank wall. Since the generator is supplying a high range current it will create a signifi-
cant voltage drop across the low resistance rod. The resistances R1 and R2 form a voltage
divider in range of the immersed part of the rod. Output from this divider will indicate half the
level of the liquid. The amplifier then calculate the actual level of the liquid from 0 to 100%.
The formula is: Uout= 1/2 x media level (%) x Ugen
Media level (%) = Uout/Ugen x 2
The level measurement is insensitive to adhesion.
Caution: It is very essential that the media conductivity is homogeneous.
Otherwise R1 will not be equal to R2 and the output voltage will be influenced.
Ugen
0%
Uout
to amplifier
100%
Level = x %
R1
R2
The Level measuring device utilises the potentiometric measurement principle and can be used in all medias that have
a minimum conductivity of 50 μS/cm.
From the low resistive measuring rod a high frequent current is fed through the media to the tank wall. The voltage be-
tween the tip of the rod and the tank wall is measured. This output voltage is proportional to the tank filling level.
The measurement is unaffected by temperature and adhesive media.
The instrument is ideal for measurements in small vessels with tough, pasty or strong adhesive media, such as ketchup,
honey, and toothpaste.
The integrated electronics provide a 4...20 mA output.
The Alfa Laval Potentiometric Level Transmitter TE67H has automatic recognition of top/buttom mounting position.
Even angled installation is possible. In a non-conductive tank such as a plastic tank a reference rod must be installed.
Please observe that a non-linear conductivity in the media will affect the accuracy of the measurement.
A version with separate rod sensor and electronics is available for applications where the ambient temperature at the
measuring point exceeds 60°C. Due to the high temperature limit the Alfa Laval Potentiometric
Level Transmitter is well suitable for CIP and SIP processes.
The hygienic installation is guaranteed by using the e.g. a clamp connection.
