Posted on 28/04/08, under Level Measurement, Principles of Good Measurement · RSS · No Comments
High frequency microwave pulses are coupled on a cable or rod and guided along the probe. The pulse is reflected by the product surface and received by the processing electronics. This electronics evaluates the echo signal and converts it into a level information. All instruments are preset to the ordered probe length. The shortenable cable and rod versions can be adapted to the individual conditions on site.
Applications in liquids
Density fluctuations, steam generation or strong pressure and temperature fluctuations do not influence the measuring result. Also buildup on the probe or the vessel wall do not influence the measurement. An ideal application is level measurement in a bypass tube where even products with dielectric values below 1.6 can be measured reliably. Also connection tubes - bypass tubes have no influence.
Applications in bulk solids
Typical problems in bulk solids such as e.g. dust and noise generation or condensation do not influence the reliability. Also the shape of the material cone or the product properties, e.g. the change from dry to wet sand do not influence the measuring result. Since the instruments are already preadjusted, setup is limited to connection of the sensor.
Posted on 24/04/08, under Level Measurement, Principles of Good Measurement, Radar Measurement · RSS · No Comments
Measuring principle of a Radar Level Gauge
The antenna on a radar level gauge generates millions of very short 1 nano second microwave pulses every second. Each pulse is directed and transmitted to and reflected from a product surface. The elapsed time period between transmission and reception of the signal at the speed of light is measured and calculated as a distance. This continuous stream of pulses gives real time level information updated and is evaluated many times a second.
Radar level sensors work with safe, low emitted power in the C and K-band frequency range. The proven ECHOFOX signal processing selects the correct level echo reliably. Adjustment by filling and emptying the vessel is not necessary, it can normally be done with simple input of vessel dimensions.
Applications in liquids
Two different emitting frequencies are available for these applications. The compact, high frequency sensors are particularly suitable for applications for which high accuracy is required. Even with small antenna sizes, an excellent signal focusing is reached. Low frequency C-band sensors can penetrate foam and strong condensation and are thus particularly suitable for arduous process conditions. Unaffected by steam, gas composition, pressure and temperature changes the sensors detect the product surface of different products reliably.
Applications in bulk solids
High frequency sensors in K-band technology are used for these applications. Thanks to the very good focusing of the signals, the influences of silo installations or buildup on the vessel wall are gated out. A high sensitivity electronics adapted to the requirements of the bulk solids measurement, enables a reliable level measurement of different products up to 70 m. The measuring principle is unaffected by strong dust generation, filling noise, air turbulence by pneumatic filling and temperature fluctuations. The application area covers applications in the food processing industry and the plastic processing up to the steel generation.
