Process optimised "valve terminal

Insulin has revolutionized the treatment of diabetes mellitus. For a good quarter of a century, the life-saving active ingredient has been produced industrially with the help of genetically manipulated bacteria and yeasts. The demands on the process technology used for this are high. Not only do the systems have to meet strict standards and legal requirements in terms of hygiene and cleaning, they also have to operate with high precision and reliability. The ZETA group of companies, headquartered in Austria near Graz, is regarded as a specialist for tailor-made process solutions for such sterile and aseptic applications. The technology supplier to the biotechnology and pharmaceutical industries designs, manufactures and installs customer-specific solutions for renowned companies around the world. An example of this is provided by a turnkey automation solution for a fermentation plant for insulin production, which will go into operation in Russia at the end of 2018 (Fig. 1). The scope of this project is considerable; 18 tanks, 30 control cabinets and the complete measurement and control technology had to be designed and installed, tested and certified. A total of 20 valve terminals from Bürkert (Type 8647 AirLINE SP) in combination with the decentralized ET 200SP peripherals, which control around 600 valve functions during the fermentation process, are responsible for the electro-pneumatic automation.

Technically and economically convincing
There were several reasons for this choice, as Andreas Rauscheder, project engineer at ZETA, explains: "As early as the planning phase, we were convinced of the advantages of the new generation of valve terminals compared to standard pneumatic solutions. The hardware and software integration into our Siemens automation world simplified installation, commissioning and parameterisation. Thanks to the option of fully parameterising the valve terminals using the HSP file in the Siemens TIA Portal, we saved a considerable amount of time and money."

Another decisive advantage of the system is the external valve voltage cut-off - EVS for short. For this purpose, the supply circuit for the load voltage of the valves is interrupted via a potential-free contact. "This allows us to safely shut down individual valve modules in accordance with the requirements of the Machinery Directive and EN13849 or the corresponding SIL requirements." By using the EVS function, individual safe emergency stop circuits can be implemented on the valve terminal with little effort.

"This saved us additional effort; if an emergency stop button is pressed by an employee, the valve terminal on the corresponding part of the system immediately goes into a safe state and the control center also knows," Mr. Rauscheder is pleased to report.

High operational reliability and availability
In addition to displaying and forwarding the EVS function, the standard integrated diagnostic function also offers other options that increase operational reliability. For example, an integrated pressure measuring module monitors the supply pressure and forwards warning as well as error messages to the control level in the event of deviations from the specified values. Likewise, switching cycle counters can be used independently for the pilot valves and the downstream actuators.

"Pilot and process valves can also be visually assigned on site for greater clarity," adds Mr. Rauscheder. Wire breakage, short circuit and open valve outputs are also detected, displayed directly on the valve terminal in plain text and as a symbol and forwarded via the communication interface of the ET 200SP.

To increase pneumatic availability, ZETA also opted for the integrated P-channel shut-off. This allows valves to be changed during operation without having to depressurise the rest of the valve terminal. The check valves, which are also integrated in the exhaust ducts of the valve terminal, also ensure feedback-free and safe switching of the process drives. "Since the valve terminals are modular, we were able to 'move' certain functions to another control cabinet at a later date. All we had to do was swap the corresponding modules and change the screw connection," continues Mr. Rauscheder.

Fast certification
Since the fermentation plant is intended for the Russian market, the EAC certificate of the Eurasian Economic Union was also required for the valve terminals. ZETA was pleasantly surprised at how quickly the fluidics experts reacted here and were able to provide the relevant documents. "The delivery dates were met exactly, the advice was right and minor software adjustments that arose afterwards were quickly dealt with," reports the project manager. Nothing stands in the way of repeating the cooperation in future projects. As intelligent electro-pneumatic automation systems, the valve terminals are not only used in the pharmaceutical industry. Very similar tasks and requirements exist, for example, in the cosmetics, food and luxury food industries or in water treatment.