Festo - 15 years without any failures

In 2002, Bayer invested around €110 million in the construction of a multi-purpose system at its site in Dormagen, Germany. This houses everything under a single roof, from the development and manufacture of new active ingredients for crop protection, as well as laboratory processing, sampling and piloting, right up to the production processes.

The system is designed so that subsystems and equipment such as dryers, centrifuges, distillers, stirrer tanks and other reactors can be flexibly connected and operated. An in-house pipeline with adaptable piping takes care of the material flows, while the decentralised process control system is distributed over 67 automation systems, thus enabling the process controls to be flexibly adjusted.

As the process development requires the use of flammable operating fluids, frequent process changeovers and numerous interfaces and intervention points, the entire system has been classified as potentially explosive zones 1 and zone 2 according to the explosion prevention and protection measures.

Minimising safety risks for people and the environment
The probability of an incident occurring at a chemical plant depends largely on the reliability of the system components and the individual processes.

This includes, for example, the availability of coolant water, electricity, emergency stop devices, stress-relief devices, pumps, mixers and process valves.

Processes can be reliably controlled when all the important elements operate correctly, from system operation to the safety functions for instrumentation and control technology.

Safeguarding process facilities in the chemical and petrochemical industry using instrumentation and control technology is thus very important.

Optimising the economic efficiency of processes
The economic efficiency of a process also depends largely on the reliability of the individual system components, and thus also on instrumentation and control technology.

As modern process engineering systems are highly optimised, increased levels of output can only be achieved with a reliably functioning, highly productive system without downtimes. This means reducing inspection cycles and inspection times, as well as avoiding idle times or downtimes caused by repairs carried out outside of the maintenance schedule.

Solenoid valves – instrumentation and control technology components with high levels of responsibility
The Bayer Crop Science’s multi-purpose system uses numerous instrumentation and control technology devices in order to switch dosing valves, exhaust valves, steam valves etc. to failsafe positions. The solenoid valves that activate the actuators must, at a very minimum, have the same SIL classification as the entire safety loop (with single-channel architecture).

A solenoid valve in a safety loop is generally placed between the positioner and the actuator and is used to quickly exhaust the actuator and close the process valve in case of an emergency.

Solenoid valves VOFC and VOFD, which Festo added to its own product range at the end of 2012 as part of a takeover of the process automation division of Eugen Seitz AG, can be supplied with TÜV certification up to SIL 3. These valves, in accordance with the latest SIL classification from TÜV Rheinland, will guarantee a failure probability rate of 2.41 E-4 and a safe failure fraction of 75%. In other words, if used properly, a maximum of one faulty operation will occur in 2,410 switching cycles.

Assuming that such safety loops undergo a failsafe inspection once a year, this means that a faulty operation will occur once in 2,410 years; so it is virtually impossible for a valve not to switch when it should. These solenoid valves are available with ignition protection types “Ex em” and “Ex ia”, and are thus especially well-suited for use in safety loops.

Tel: 0800 626 422
Email: info_gb@festo.com
Web: www.festo.co.uk

Spring 2020 // Issue 52
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