Today, level measurement technology is the basis for management and process control in the chemical, petrochemical, environmental and other related industries.
Our comprehensive program enables us to help you solve your particular measurement and control problems and to detect the precise level of any medium, under a wide range of conditions.
I. Limit Detection:
1, Float Switch:
Float switches are used for simple limit value detection in liquids. Due to the higher density of the liquid, the float switch floats on the liquid surface. The float switch is secured by means of its cable fastener at a level suitable for the given application. The switching process is triggered by the rocking movements of the sensor. Initiators and micro-switches are used as switching elements.
2, Vibration Limit Switch:
The piezoelectrically activated vibration of a vibrating fork is damped when the fork comes into contact with the medium. Using this change, an electronic system determines the switching signal. The function is independent of fluctuations in the physical properties of the medium.
3, Conductive Limit Switches:
The conductivity of a liquid medium may vary widely. Once the liquid reaches the fill limit determined from the installation height of the electrode, the liquid medium closes the DC free alternating current circuit between the two electrodes (or between the container wall and an electrode). A switching signal is produced from the sudden increase in current consumption.
Acids, lyes and solutions containing water are conductive and are detected very well. Aggressive liquids can be detected without problems using probes made from highly-resistant materials. Combustible liquids such as fuels, oils and solvents are nonconductive and cannot be measured by this measurement principle.
4, Capacitive Limit Switches:
An insulated metal probe mounted in a metal container forms a capacitor together with the metal wall whose capacitance continually increases as the medium level increases. Hence, for capacitive measurements a medium with a constant permittivity is required.
The simple and robust construction (as rod or rope sensor) allows level measurement of liquids, granular solids, conductive and non-conductive media.
5, Magnetic Immersion Probe:
Magnet-operated immersion probes are used in clean liquids, such as solvents or oils. The float, guided by a probe tube, floats on the liquid surface. By means of its magnetic field, the ring magnet built into the float activates the reed contacts installed in the guide pipe. These are switched when the float is located in the appropriate position.
The reed contacts are designed as normally closed, normally open or change-over contact switches. The measurement is independent of the electrical properties of the liquid, pressure, temperature and density.
II. Continuous Measurement:
Continuous level measurement
Level measurement sensors detect the current fill level. This is done by determining the distance from the surface of the medium to the preset reference level. Continuous level measurement allows usage evaluation, loss control, and above all, precise process control (VDI/VDE Directive 3519).
1, Magnetic Immersion Probe:
A float moves along a vertical guide tube. The permanent magnet fixed in the float switches the contacts of a reed contact resistor chain. This resistor chain acts as a voltage divider and provides the voltage values corresponding to the medium level. The resolution is dependent on the number of contacts used. The measurement is independent of the electrical properties of the filling material, as well as the pressure, temperature and density.
2, Hydrostatic Pressure Sensors:
The pressure in a liquid increases with increased filling height. This hydrostatic pressure is transmitted to the measuring cell via a stainless steel diaphragm. Foam, build-up, fluctuating electrical properties of the liquid and the container design do not affect the measurement values.
The fill level of a liquid can be determined by the hydrostatic pressure if the density is known. The piezoresistive measuring cell is coupled to the measuring liquid via a stainless steel isolation membrane and diaphragm seal.
The value of the measuring cell can be converted via a signal conditioner into one of the following output signals:
- 4 ... 20 mA analog signal
- 4 ... 20 mA analog signal with HART
- PROFIBUS PA digital signal
The pressure sensors are available in the following versions:
- Externally mounted type
- Rod type
- Suspended type
3, Ultrasonic Level Sensors:
The level height is calculated from the time it takes for ultrasonic pulses to travel from the sensor to the surface of the medium and back. Chemical and physical properties of the medium do not influence the measurement result. Therefore, aggressive and abrasive, viscous and adhesive media can be measured without problems.
This continuous level measurement is based on the travel time of ultrasonic pulses to the surface of the medium and back.
When installing the sensor, the typical block distance has to be considered. Rough liquid surfaces and the changed angle during filling and emptying granulated solids influence the reflection of the ultrasonic pulses and may impact measurement.
4, Guided Level Radar:
The system is based on the reflection of an electromagnetic pulse that is directed on a sensor rod/ cable and reflected by filling material. The electronics integrated into the sensor determines the filling state from the echo time of the pulse and shows this in the display.
The electromagnetic pulse is sent out, reflected on the filling material and received again. The echo time of the pulse is proportional to the distance from the surface of the medium. The measurement procedure and the accuracy of the measurement are independent of pressure, temperature, vapor, dust, foam, viscosity, conductivity and pH value.