In process technology, automated systems are designed for many years of operation. The minimum requirements for the safety standards of machines and plants are now regulated in the Machinery Directive 2006/42/EC, but are subject to constant change. The aim: to protect the life and health of persons, e.g. when work is carried out on pipelines, valves, connectors or similar. Danone GmbH was able to easily retrofit the required safety standards in the existing system - thanks to the new Bürkert valve types for safety-related shutdown.
Simple retrofitting of the required safety standard
Danone GmbH produces mainly yoghurt and desserts for the German market and for export to neighbouring European countries. In order to meet the new safety-related requirements for maintenance, repair and cleaning work, significant optimisations of the existing safety concept were necessary. The existing safety standards were already quite high - emergency stop switches were locked, for example, during a shutdown with locking mechanisms to prevent accidental resetting. Certain valves could be switched off from the control system via Profibus in the widely ramified pipe system between the 16 tanks and the six filling lines.
The aim was to achieve a quite high Performance Level C for this application. Especially for cleaning work, those responsible wanted the highest degree of safety, as cleaning agents containing acids and alkalis at temperatures of up to 80 °C are used. If a section of the pipeline, e.g. when cleaning the screens used, were not reliably shut down or an electrical or mechanical safety measure were circumvented, serious injuries to the employees would be quite possible.
The practical solution to costly replacements and unwanted downtime
The starting point: The system consisted of a decentralized peripheral system from Siemens (ET 200S) and the pneumatic output modules from Bürkert integrated therein, which were mounted close to the process in stainless steel control cabinets. With these valve terminals of type 8644, electrical and pneumatic signals can be controlled via a bus line.
The objective: A control error via the Profibus must never cause certain valve functions to be activated unintentionally, while employees on site carry out necessary work on the piping system. Typically, such requirements are solved via a Profisafe controller, the Profisafe protocol and corresponding fail-safe IO modules. However, such a conversion is time-consuming and involves unwanted downtimes and the costly replacement of numerous components.
The solution: Switch off certain valve functions safely directly on the existing valve terminal - i.e. on the pneumatic modules on the ET 200S. For this purpose, valves can be retrofitted with an additional connection for safety-related shutdowns. Want to learn more about Bürkert's solution for Danone? Just download the flyer!
Safety with pneumatic valves from Bürkert
The new Type 6524 and Type 6525 pneumatic valves with additional shut-off function can be shut off independently of the regular switch signal control of the valve island. Valve integration is possible at any valve slot on the valve island. The valves consist of a pilot flipper solenoid valve and a pneumatic seat valve. The flipper action system allows the switching of high pressures combined with low power consumption and fast switching times. The patented shut-off function is implemented via a second connection.
The valves are still controlled via the bus but additionally offer a second electric connection via which the power circuit of the solenoid coil can be interrupted. When triggering a safety chain, the normally closed contact of an emergency stop relay shuts off the coil of the pneumatic valve, irrespective of valve activation by the PLC.
Ensure safety in your plants. Inform now about the advantages of our pneumatic valves!