Getting the most from steam control valves

25 October, 2016

Process control in hygienic applications, such as the food and beverage sector, demands a great deal from the components that are used to manage the manufacturing and cleaning processes. Choosing the right steam control valve can bring a number of benefits including precision, reliability, minimal maintenance and durability in challenging environments.

Steam control valves play a vital role in food processing and as such are usually located in areas that require hygiene standards to be maintained both through external cleaning processes and internal sterilisation methods. The most common material used in these environments is stainless steel, which is widely regarded as a strong material that has good chemical resistance properties and is easily cleaned. Furthermore, stainless steel does not require painting in order to maintain a hygienic surface, which is so important in this industrial sector.

Compact footprint

While external design is important, the precision and reliability of a control valve is determined by the internal design and construction, which is established by the expertise of the engineers who created the valve. A more traditional approach uses a diaphragm which requires a larger surface area to operate and consequently the valve housing is much larger and heavier. In contrast, a piston actuator requires a much more compact footprint, requires less material and is more efficient in terms of air consumption.

Precision and reliability are crucial in any control system and the designers at Bürkert have used high-gloss, polished valve stems to minimise friction and maximise the service life of the automatic, self-adjusting seals. In addition, 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. Finally, because the feedback transducer is fully protected inside the valve, the requirement for external linkages, nuts, bolts and connections is eliminated, maintaining the clean lines of the exterior valve casing.

The actual control process is usually operated pneumatically and this can introduce further challenges in terms of hygienic performance and durability. There is a significant potential for ambient air to be drawn into the actuator, where it can lead to corrosion and biological growth that may contaminate the system under control.

Extended reliability and life

Bürkert designers have completely removed these risks and improved on the traditional concept of reliability with the development of the Element valve controller. For each operation, clean and dry control air is deliberately flushed into all areas of the actuator, ensuring that, unlike traditional solutions, ambient air is never drawn into the spring chambers and surrounding voids. This extends the valve’s reliability and life, at the same time maximising process availability for the valve user.