Tried and tested solenoid valve technology

The products of the Bayer’s Division Crop Science secure and boost crop yields in more than 120 countries. The new multi-purpose facility built by the company had to meet extremely strict demands on safety and reliability. Inspection cycles had to be significantly reduced, and downtime caused by repairs was to be entirely eliminated in the future. To achieve this, Bayer relied on valve technology from Festo. The facility has now been running smoothly for such a long time that the German Technical Control Board (TÜV) has issued Festo with a certificate for unlimited use of its valves.

Bayer’s Crop Science Division develops active ingredients for crop protection as well as the relevant production processes. The manufacturer wanted to bring all the necessary processes under a single roof so that products can be produced faster and more individually. As a longstanding business partner and automation specialist, Festo was invited to get involved in the planning an early stage.

The project turned out to be a demanding task for the engineers. Bayer designed its new facility so that subsystems and equipment can be flexibly connected and operated. The process control system is broken down into 67 automation systems, so that process control can be flexibly adapted as well. At the same time, additional demands were placed on explosion protection. Not only does Bayer process flammable liquids during operation at its facility, the ongoing process development also necessitates numerous interfaces and intervention points because processes are frequently changed. As a result, the entire facility was classified as potentially explosive zones 1 and 2.

Requirements for safe multipurpose facilities

Minimising safety risks

The more reliable the components and processes are, the safer the overall chemical plant is. This includes the availability of coolant water as well as electricity, emergency stop and pressure-relief devices, pumps, mixers and process valves. The functional safety of all processes depends on the correct functioning of all important elements, from system operation to the safety functions for instrumentation and control engineering (ICE).

Specially tried and tested ICE components are decisive for the safety of process systems in chemical and petrochemical plants. They not only help to avoid overpressure and other dangerous system states, they also enable trends to be detected at an early stage so that effective countermeasures can be implemented (in some cases automatically). For example, a runaway reaction can be detected by calculating the temperature gradient.

Optimising economic efficiency

The more reliable the ICE components are, the more efficiently the process system functions. Even if a process engineering system has already been largely optimised, increased output is still possible with a system without downtime. Tried and tested ICE components, certified to IEC 61508, reduce inspection cycles and inspection time to a minimum and ensure that no unplanned downtime occurs due to repairs. As a result, the entire facility remains productive continuously.

Highly reliable solenoid valves

Bayer Crop Science's multi-purpose facility includes numerous ICE safety devices from Festo. Amongst other functions, they switch dosing, exhaust and steam valves to failsafe positions. This in turn has consequences for the solenoid valves that control the actuators: they must (for a single-channel architecture) have at least the same SIL classification as the entire safety circuit.

In practice, the extremely low demand mode represents a special challenge for the engineering design and the components used as a solenoid valve is usually built for several million switching cycles. In a safety circuit, on the other hand, it may be energised for decades under certain circumstances and must still react reliably in case of emergency. In scenarios like that, you are only on the safe side with components that have proven they can withstand the ravages of time.

Solution: solenoid valves VOFC/VOFD

Bayer needed a universally usable and compatible solenoid valve that could deal with all sorts of conditions in the process industry. The valve would also have to meet the requirements for control in intrinsically safe circuits (Exi) in zone 1. Our high-end 3-way solenoid valve from the VOFC series precisely meets these demands. We supply it with an approval certificate from the German Technical Control Board (TÜV) for up to SIL 3. Our 5-way solenoid valve VOFD guarantees a failure probability rate of 2.41 E-4 and a safe failure fraction of 75%. This translates into a single switching fault during 2410 switching operations. If the valve comes up against one failsafe operation per year, only one switching fault could be expected over a period of 2410 years – i.e. it is virtually impossible for the valve not to switch in case of emergency. Solenoid valves VOFC/VOFD, which are available with ignition protection types Ex em and Ex ia, are thus ideal for use in safety circuits.

Unlimited use

Bayer is not the only company that is very satisfied with our products. The multi-purpose facility has demonstrated that this faith in our products is justified. More than 1500 solenoid valves from the VOFC series were installed, in safety-related as well as other control circuits. To date, none of these components has failed, nor is there even the slightest indication that they will. 14 of these valves were also subjected to an endurance test in 2015, the results of which have led the German Technical Control Board TÜV-Rheinland to issue a new certificate. Since then, Festo is the first company to be able to forego any reference to a limitation of the valves' service life. Of course, you always must implement the necessary precautions to avoiding errors, and ambient conditions also have to be taken into consideration. But in principle, you, as the system operator, specify the duration of use of our certified solenoid valves VOFC yourself.

Zero-leakage compressed air supply

Another Festo product that has been paying off for Bayer for many years is the polyurethane tubing in combination with the push-in fittings NPQH. It is used as compressed air supply lines for the solenoid valves. It is quick to assemble and flexible in installation. The tubing clip mechanism in the fitting has an integrated sealing ring which prevents the loss of compressed air and can be quickly released if necessary.

Other advantages for Bayer are the tubing’s strong resistance to UV radiation and its resistance to chemicals. We can supply tubing in various colours, making identification by the customer unnecessary if nitrogen is used in addition to compressed air. Thanks to our bulk packs, there is no need for connector fittings even when long tubing lengths are required. This reduces the possible number of leaks to an absolute minimum.

Bayer AG
Crop Science Division

Alfred-Nobel-Straße 50
40789 Monheim am Rhein

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