en.Wedoany.com Reported - German building materials supplier Sto has replaced silo weighing systems with VEGAPULS radar level sensors to improve the reliability of measuring raw material and finished product inventory.
Sto considers on-time delivery as one of its main quality standards, and reliable inventory level measurement is key to achieving this. Since 1965, Sto products have saved energy equivalent to 130 billion liters of heating oil and prevented approximately 416 million tons of CO2 from entering the atmosphere. With over 30,000 different products, Sto's plant in Torwitz supplies dry powder products such as adhesives and composites to central and northern Germany. Raw materials for production and finished products must be delivered quickly, and the logistics department must precisely know inventory quantities.
The company has limited storage facilities, with products stored in different silos. Sand and cement are stored in large raw material silos, while finished products are kept in smaller silos in adjacent auxiliary buildings. Previously, the silos were equipped with load cells to track inventory, but this method was not accurate enough, often resulting in discrepancies of two tons or more per silo. The main issue with load cells is that each silo itself weighs over 100 tons, making measurement errors particularly prone during the filling process.
In search of an alternative, Sto evaluated radar level measurement technology and ultimately adopted VEGAPULS radar sensors. The advantage of this sensor lies in its transmission frequency of 80 GHz and an antenna with a diameter of approximately 75 mm and a beam angle of only 4 degrees, allowing measurements to be unaffected by deposits on side walls or internal installations. The VEGAPULS 6X is widely used in the bulk solids sector, especially in the building materials industry, providing continuous measurement unaffected by filling and emptying processes. The sensor also needs to handle the "settling curve": when a silo is filled, air is carried in with the material, and the instrument must react quickly—sometimes more material is added within just one minute. Additionally, parameterization and commissioning must be simple to accommodate varying bulk densities.
After a three-month testing phase, the VEGAPULS radar sensor was approved. Sto decided to equip not only the finished product silos but also the raw material silos simultaneously. This solution not only provides reliable measurement results but also allows the same measuring instrument to be used in different locations, enabling plug-and-play operation. Installation requires planning for power supply and Profibus cables or flanges, but the sensor itself is easy to install, and Sto completed all setup on its own within two days. The VEGA Tools app for smartphones helps determine the correct tilt angle for sensor installation.
Almost all sensors have worked reliably since commissioning, providing accurate measurement values. The VEGA instruments display the filling level as a percentage, and the software converts this into tons, with the inventory management system providing additional production safety. One specific silo storing raw materials with low bulk density presented measurement difficulties; gaps in the silo wall generated false echoes, and the echo curve was complex even when the silo was empty. After repositioning the sensor and adjusting parameters, this measurement point has been functioning normally.
For Sto, the decisive factors in choosing the sensor were its high performance and versatility, including rapid adaptation to environmental conditions and accurate display of measurement values when the silo is simultaneously filled and emptied. VEGA's customer service was also recognized, as the team always received timely support whenever they encountered issues.
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