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Alternative to diaphragm

Shut-off valves with bellows for sterile processes
Alternative to diaphragm

Vesta sterile valves meet the operational requirements for pharmaceutical and biotech processes, comply with the strictest safety regulations and provide a high-quality product. The most important features of the innovative design are hermetic and safe sealing by PTFE bellows with a patented sealing system, actuator systems made of high-grade synthetic material or stainless steel and easy servicing. With these valves the German manufacturer Tuchenhagen offers a cost-effective alternative to diaphragm valves.

Werner Schmid

The Vesta sterile valve (Fig. 1) provides the market with a valve series for low volume flow rates, suitable for applications from laboratory up to highly complex process plants. The valves prevent product contamination from the outside, ensure that the process system stays free of germs and offer the following design benefits (Fig. 2):
  • Pocket-free design without domes or pools
  • Valve body drains completely in straight pipes
  • PTFE bellows as shut-off element for universal applications
  • Long service life of the PTFE bellows
  • Patented bellows sealing system hermetically, safely and permanently seals off the valve interior against the outer atmosphere
  • Compact design due to newly developed actuator systems
  • Reliable CIP/SIP cleaning thanks to optimised flow characteristics
  • Hygienic outer design, meets EHEDG/cGMP standards
  • Simple and safe maintenance
Size – a decisive factor
Some years ago, Tuchenhagen already set standards in sterile process technology with its Stericom aseptic valves in DN 25 to 100 (DIN) and 1“ to 4“ (OD) sizes. For processes in the pharmaceutical, food and biotech market segments, these sizes were hardly ever used, as process systems in this sector usually require much smaller volume flow rates. Diaphragm valves were employed almost exclusively for low flow volumes, as adequate valves with bellows were not previously available. The Vesta sterile valve series makes these small sizes accessible for different pipe standards:
  • DIN – pipe standard DIN 11850, series 2: DN 10, 15, 20 and 25
  • OD – pipe standard ASME BPE 1997: ½“, ¾“, 1“
  • ISO – pipe standard DIN EN ISO 1127: 13.5 x 1.6/17.2 x 1.6/21.3 x 1.6/26.9 x 1.6/33.7 x 2
Patented bellows sealing system
The heart of the Vesta sterile valve is the PTFE bellows made of Hostaform TFM X 1705 (Fig. 3). In addition to its outstanding chemical resistance to almost all types of media, Hostaform TFM X 1705 is approved in accordance with the Code of Federal Regulations, Title 21 § 177.1550 “Perfluorocarbon resins“ of the Food and Drug Administration (FDA). The high-quality surface (Ra <0.8 µm), the gap-free, hermetic seal and the special design for optimum CIP/SIP cleaning are the characteristic features.
The patented bellows sealing system ensures that the valve interior is permanently and hermetically sealed off against the outer atmosphere, even during critical phases of the process. As shown in figure 4, the special features of this bellows sealing system are:
  • Sealing by a thin-walled sealing dia-phragm (1)
  • Permanent compression by an elastomer O-ring (2)
  • Under excess pres-sure conditions, product forces are compensated by a metallic thrust collar (3)
  • Under vacuum conditions, protection is provided by a circlip (4)
  • Defined pre-tension by metallic stop (5)
The valve body – a variable basis
The valve bodies of the Vesta series are made of solid material and are available in 1.4435 ( AISI 316L ) with a delta ferrite content <1%. Valve bodies are generally supplied with a material certificate according to EN 10204/3.1B and have markings in accordance with AD instruction sheet A4. Bodies made of higher-grade materials (1.4539, Hastelloy, etc.) are available on request. All valve bodies are fitted with pipe sockets that are suitable for orbital welding using orbital cartridge systems.
In addition to body types L (two sockets) and T (three sockets), other body variants (body types E/C/B/A) are available for special applications (e.g. sampling from ring mains systems).
Actuators made of synthetic material and stainless steel
For the first time, Tuchenhagen offers single-acting pneumatic actuators made of synthetic material for automated processes. The actuator system is made of the high-performance material PPS. This material has a good chemical resistance, is temperature resistant up to 180 °C, has good mechanical properties and is highly resistant to ageing. The actuator system is easy to maintain. Thanks to the special design, there is no risk of spring tension being relieved during dismantling. The actuator action is reversible, conversion from spring-to-close to spring-to-open or vice versa is possible and can be done easily on site. Pneumatic actuators in the Vesta series are already provided with integrated air connections for plastic hoses, dia. 6 x 1 mm, as well as visual detection of the valve position. A relief hole separates the actuator and product cavities, thus preventing contamination, and serves as a leakage outlet in the event of actuator defects or breakage of the bellows.
Vesta sterile valves are also available with a pneumatic actuator made of stainless steel, with the same design features as the PPS actuators. Stainless steel actuator versions that are suitable for autoclave sterilisation can be supplied on request.
Vesta sterile valves with a manual actuator (Fig. 5) are available for manual processes. The special feature here is the design of the manual actuator. An integrated spring package ensures defined compression of the PTFE bellows seal in the closed position and prevents unintended deformation of the bellows. The spring force only becomes effective shortly before the closed position is reached; in intermediate positions, manual valves can be operated with minimal effort. Any alteration of the bellows seat contour due to influences by the process will not cause leaks – the spring adjusts automatically. Vesta sterile valves with a manual actuator can be provided with a lead seal.
Optional equipment
With pneumatically operated Vesta valves, an electrical control module for feedback of the valve position is available as an option. The electrical control module can be equipped with inductive proximity switches (3-wire technology) for an operating voltage of 10 to 30 V DC or alternatively with NAMUR proximity switches (DIN 19234/EEXi) for an operating voltage of 8 V DC. Integrated LEDs signal the operating status and the valve position. The control module is fitted on top of the actuator. Setting/adjustment of the switch points is completed in next to no time.
Service and maintenance
A major feature is the easy on-site service and maintenance. For routine inspections or to replace the PTFE bellows, simply release the groove nut, remove the complete valve insert from the body – and that’s that. Vesta sterile valves do not have any loose fixing elements and the groove nut is firmly connected with the valve insert. All service work can be performed with standard tools no matter whether you are replacing the bellows or servicing the actuator systems.
Hygienic design – also on the outside
Special attention was paid to a hygienic outer design when developing the Vesta series. The design of the closed lantern, with self-draining surfaces (without cavities or gaps) irrespective of the valve installation position, ensures a lasting, hygienic valve exterior, even if soiling makes exterior cleaning necessary.
In product-contacting areas, Vesta sterile valves generally have an inner surface roughness of Ra <0.8 µm (optionally electropolished); the outer surfaces have bright/finish-ground finish. Higher-grade surfaces are available on request. Vesta sterile valves are also suitable for use in clean rooms.
Repeatable manufacturing quality
Vesta sterile valves are produced in accordance with the highest quality standards. This is guaranteed by Tuchenhagen’s quality assurance system, which is certified according to DIN ISO 9001. Permanent quality tests in the workshop, marking of all components and valve identification by means of a type plate with a serial number are among the features that ensure a constantly high quality level and enable reliable tracing if spares are required.
Vesta sterile valves can be supplied with certificates for the following quality characteristics:
  • Body with material certificate according to EN 10 204/3.1B
  • Surface roughness documented by factory test certificate according to EN 10 204/2.2
  • Delta ferrite content documented by works certificate according to EN 10 204/2.1
Economical distribution systems
Distribution systems equipped with Vesta sterile valves are also available (Fig. 6). They meet the well-known requirements of complex process technology with different operating, cleaning and sterilisation media.
Distribution systems incorporating Vesta valves have no dead space, allow complete draining, can be installed in confined spaces and offer outstanding economic efficiency.
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