Hygienic Processing: Elimination of dead space volume

Thanks to high functionality within minimal space, multiport valves ensure compact processes, facilitate excellent cleaning and increase process reliability therefore contributing to improved product yield.

Hygienic processing places high demands on the reliability and cleanability of production facilities. These requirements are especially high in separation processes like filtration and  chromatography and are significant in ensuring purity of media by maintaining sterile process conditions. The mixing of different media in the manufacture of nutrient solutions processes like fermentation demands absolute sterility. Common challenges such as corrosion in pipe systems, valve manifolds and tank installations in different pharmaceutical and biotech facilities can be reduced by using multiport valves and complex multiport-based manifolds. Multiport solutions such as the Robolux valve solution from Bürkert Fluid Control Systems were developed with such high-purity installations in mind.

Based on diaphragm valve technology the new generation of patented valves combines' independent dual process switching functions or "2 seats" in a single body with a single diaphragm and single actuator. The actuator has independent pistons - one for each seat offering a compactly designed multiport valve requiring about 40 percent less space than traditional valve manifolds using conventional diaphragm valves. Since less material is used in the body they can be heated more quickly to the sterilization temperature required to destroy microorganisms. A low internal volume and elimination of dead space supports faster cleaning and of course means better process efficiency and higher product yield from the process. Continuing the benefit of minimum space requirement the overall number of valves, T-piece, weld joints and pipe runs are greatly reduced. The result is an optimized space footprint that enhances process efficiency, reduces installation and maintenance costs and minimizes downtime.

Custom valve solutions

Robolux multiport valves with a nominal width of up to 50 millimetres are ideal for use in processes with large product quantities and accordingly large pipe diameters. Processing facilities with large tanks and piping systems need a lot of space. With multiport valve technology, such processes can be designed more efficiently with lower space requirements because one multiport valve replaces two conventional valves including the T-piece.

Bürkert supports its customers in design and implementation of the fluid part of their processes. Experienced hygienic processing experts design the valves and manifolds required based on individual customer requirements. Up to five Robolux valves can be mounted on one block. "In designing the system we take into account factors such as flow direction and flow paths of the media, self-draining and angles of inclination as well as overall geometric specifications relating to maximum dimensions and position of connections. This is possible only in very close cooperation with the customer," Alexander Equit, sales engineer at Bürkert Fluid Control Systems, explains. His team does more than just select and deliver the required valves. "We cooperate with the customer to determine how we can optimize the process and then we design the valve solutions so they fit perfectly" Occasionally, the design of the manifolds has to be modified to generate optimal fluid properties. If necessary, 3D models for the solutions are delivered to support the design process. "Of course, standard valves from the catalogue are also suitable for less complex processes. However, that is generally less than optimal. Because with customized modification we can always still optimize the process," explains Equit and adds: "To do so, we do not necessarily have to be familiar with all details of the entire production process. The individual components of the valve manifolds and their functions are sufficient."

Cleanability

The cleanability of a pipe system is influenced by dead space volumes and the application of the xD rule. Currently, the industry is satisfied with the 3D rule. Its consistent application ensures sufficient flushing for many processes. The dead legs will be completely flushed and cleaned only if the length of the dead legs is less than three times the diameter of the main pipe. Johannes Eichert explains "It is usually not possible to consistently implement the 3D rule when arranging complex configurations with conventional valves; the goal of any plant operator and planning engineer is to remain well below the requirements of this rule." The ideal solution would be to achieve the 1D rule and now the Robolux valve solutions are capable of this. The internal volume of the valves and/or valve manifolds is significantly smaller than in conventional valve solutions and there is no dead volume inside them. Eichert continues "If we weld four conventional DN15 diaphragm valves in a typical steam cross configuration we have an internal volume of 90 millilitres held in the pipe section between the 4 valve seats. If we enhance the solution by using a standard valve block we can reduce the internal volume to 50 millilitres and if we replace the standard block with the unique Robolux valve, the total inner space volume is only 22 millilitres. Robolux valves therefore minimizes not only the required installation space but also the amount of flushing agent needed and time - with significantly improved cleanability. Robolux tank bottom valves ensure entirely new properties, such as the elimination of branch lines and contamination on the bottom of the tank - depending on their use as a switching valve, sampling valve or CIP/SIP valve.

Prevention of corrosion

The cleanability of the pipes and valve manifolds is also extremely important for another reason: Improper flow through the body may result in corrosion which is a serious problem in production facilities. The cleaning or replacement of the corroded equipment entails great expense and lengthy downtimes. The use of Robolux valve interfaces can effectively help prevent corrosion. "We make sure that all valve interface areas are well flushed. This is confirmed by means of riboflavin or uranine tests in our in-house test facility that allows us to simulate the actual operating conditions," says Alexander Equit.

Process reliability and availability

Valve interfaces must meet high standards to guarantee reliable processes and yet remain flexible for different applications. Robolux valves can provide a "double block and bleed function" to prevent steam used for sterilization of the parallel line from contaminating the product and vice versa; it is achieved by using a relief valve in between the 2 seats. Multiport valve bodies genuinely enable the effective implementation of many complex applications. For example, parallel operation is possible with the use of a Robolux DFP (Double Flow Path) interface which increases overall availability of the plant and saves production time.

They can act as a reliable sterile barrier in the fermentation process; a solution using two actuators and 2 diaphragms provides the function of steam barrier with 4 connections and 4 seats that replaces four conventional valves with their single actuators each and the corresponding piping and connecting elements. In this way, Robolux multiport valves contribute significantly to cost reduction in hygienic processes.

Robolux valves - facts and data

• Optionally pneumatically or manually controlled
• Nominal widths from DIN DN08 to ISO DN 50
• Three actuator and diaphragm sizes: RV50 / RV70 / RV110
• Operating pressure from 0 to 10 bar
• Body materials: 1.4435 stainless steel (316L), Hastelloy, titanium, PVDF or PP
• Diaphragms: EPDM, Teflon^â PFA/EPDM, FKM, silicone, Technoflon^â PFR91

Press contact:

KÖHLER + PARTNER GmbH
Stefan Munko
Am Flidderberg 48
D-21256 Handeloh
T: +49 (0)4188-8921-0
F: +49 (0)4188-8013
E: stm@koehler-partner.de
www.koehler-partner.de