Stainless steel control valves for food & drink!

Rust, corrosion, dirt, flaking paint, water ingress and external integrity impaired by aggressive products, would all be high up on any process engineer’s list of typical application problems for valves in the food and beverage industries. Many would say that these industries have, for too long, been plagued by these problems, to the extent that companies have learned to live with them.

Buerkert’s ELEMENT System

The new ELEMENT control valves are part of Buerkert’s ELEMENT system, which has set a higher benchmark in process measurement and control. ELEMENT provides a complete systems approach, linking clean line valves, sensors, positioners and valve actuators in a simple architecture to solve total control loop processes. With unlimited modularity, ELEMENT saves processing time by offering total control solutions for media from slurries to steam, and from de-ionised water to hydrochloric acid.

Now, however, the limitations of conventional control valve solutions in the control of steam, fluids, gases and aggressive media that play a central role in the processing of food and beverages, have been thoroughly and systematically analysed by Bürkert. The result of this evaluation is the ELEMENT series of control valves. The innovative features of these attractive, clean line, stainless steel valves meet the challenges of process industries – including hygienic processing sectors - and offer solutions to problems that many users have hitherto accepted as system-intrinsic.

In addition, as an added benefit, the valves also satisfy the pressing industry need to reduce energy use. Thanks to intelligent internal design, the air consumption to actuate ELEMENT valves is up to 40% lower in comparison with conventional process valve systems.

The bodies of these control valves are manufactured exclusively from high-quality stainless steel, a material that not only saves on weight, but also considerably enhances the aesthetics of the valves. In comparison with other materials, stainless steel is a convincing choice, as its cast integrity is high. This means that the valve walls can be optimised, reducing their overall weight and size envelope. Moreover, the impact resistance of stainless steel can be up to 25 times higher than other materials. What all this means for the valve user is more lightweight, compact and robust valve bodies.

The use of stainless steel offers longer term advantages, too. When the finish on most conventional valves has been damaged by exposure to harsh process environments, they still retain their original attractive appearance.

Designed to IP 65/67 protection class, the ELEMENT control valves, with their heat and chemical resistant design, easily withstand the rinsing and cleaning processes required in food and beverage plants. The clean, sleek external lines ensure the valves are easy to clean and also stay cleaner for longer.

The interior of the control valves proves that outer appearance and inner values are not mutually exclusive. There are a number of innovative key operating areas. Firstly, high-gloss polished valve stems minimise friction and maximise the service life of the automatic self-adjusting seals. Secondly, the valve stroke position feedback transducer is not only integrated within the valve, but is also contact-less. Consequently, it never blocks or wears out, and always remains accurate because it measures the linear stroke motion directly without conversion. Thirdly, because the feedback transducer is fully protected inside the valve, the requirement for external linkages, nuts, bolts and connections is eliminated. This innovation dramatically reduces the areas where product can accumulate and cause contamination. Fourthly, the control air is also routed internally, without the need for awkward external hoses.

A further innovation on these units is valve actuator control, which is achieved by means of the integrated pilot valves that can also be actuated manually for easy local operation. For each operation, clean and dry control air is deliberately flushed into all areas of the actuator. This ensures that, unlike traditional solutions, ambient air is never drawn into the spring chambers and surrounding voids, extending the valve’s reliability and life, at the same time maximising process availability for the valve user. In addition, as no impurities or moisture are drawn into the actuator, there can be no corrosion of the springs inside the actuator. The same feature also prevents the risk of biological growth, which could result in contamination of the process environment as a whole.

Burkert has also deployed new design thinking to provide protection against moisture ingress into the electronics of the control heads on the ELEMENT valves. Protection is required because small but naturally occurring changes in the control head pressure can lead to the penetration of moisture, particularly after a wash down cleaning process.                                                                                 …

Defence against this ingress is provided by diverting a small amount of clean control air into the control head, maintaining a slight positive pressure, thus achieving a simple, innovative and class-leading solution.

In addition to their many operational benefits, the ELEMENT valves offer optimised interactiveness with the user. The valves integrate a modern operator concept that is intuitive and user-friendly, despite the extensive range of relevant functions provided. To prevent data overload, additional functions are displayed only as required, and the configuration of positioners and process controllers is seamless and automatic. Local communication is achieved at a glance via a high-performance and highly visible, multicoloured LED display that illuminates the surrounding area, passing on immediate user information regarding the valve status. Finally, all important data logging information is displayed on a backlit graphic display.

The integrated intelligence in the ELEMENT units also means that communication outside of the local sphere is easy to achieve. With the ELEMENT control valves series, Bürkert offers a complete automation concept for integration into most commonly used control systems. Employing options, such as Profibus DPV1, ASI and Device NET, possible applications range from monitoring simple control tasks and the integration into complex field bus solutions, through to the complete decentralisation of a plant-wide automation system.