RFID in Zones 2 and 22

Depending on the application, dispersion powder must be manufactured in different grain sizes. To ensure and document this process, WACKER in Burghausen has for the past year been identifying the mesh width of its tumbler screens with Turck's BL ident RFID system, which is also approved for use in dust hazardous areas. As a result of its good experience with this system, the company is also now equipping the first coupling stations with it.

The most important production site for, idyllically situated on the Austrian border, in the so-called ‘Bavarian chemical triangle’. The chemical plant, covering a two kilometer area, employs 10,000 people in around 150 facilities, and produces thousands of different products.

In Burghausen the chemical company WACKER produces dispersion powders that are added to tile adhesives, plaster, screeds and other building materials so that they are given particular properties. To produce the end product, a liquid is dried in a drying tower at the end of the production process. The resulting powder then has to be vibrated through a screen before it can then be packaged. This ensures that the product concerned has the required grain size.

In order to increase transparency and traceability in the production of dispersion powder, the production plant expressed the wish for the automatic detection of the screen size used in the tumbler screens. “The correct screen size was previously measured manually by colleagues in the plant,” Michael Holzapfel, plant engineer responsible for electrical engineering in the Construction Polymers division, explains. “In order to exclude the possibility of human error, the screen used for each batch now has to be measured automatically. This enables us to not only guarantee the 100% quality of the ongoing process, but also to have a retrospective record of the correct screening process.”

Due to the particular environmental conditions at Burghausen, WACKER gradually came to the idea of using an RFID solution. The solution nevertheless had to be approved for use in the dust Ex zone. “Turck was the only manufacturer that could offer us an RFID system that is Ex-approved for zone 22 dust,” Holzapfel describes the original reason for choosing the system of the Mülheim automation specialist.

Up to now WACKER has fitted four tumbler screens with a type TNLR-Q80-H1147-Ex read/write head that is approved for use in Ex zones 2 and 22. All the screens used there were fitted with a TW-R50-B128-Ex tag on which the mesh width is stored. The disk-shaped tag is fitted at the edge of the screen, directly under a strap with the optical marking of the mesh width. The read/ write head reads the mesh width and passes on the data to the process control system via Profibus using one of three BL20 I/O stations.

During the course of the installation yet one other hurdle had to be overcome: “The function block supplied with the RFID system is programmed for a Siemens S7 PLC and not for a Siemens PCS7 process control system like we use here,” Holzapfel explains. “However, our software specialists worked in close collaboration with Turck Support to quickly adapt the S7 function block so that it can now also run on the PCS7.”

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RFID in Zones 2 and 22

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