Chemical Technology October 2015

PUMPS & VALVES

Diaphragm valve in a plant for producing agents

made from forgedmaterials to ensure high steel homogeneity and to avoid the risk of cavities in the material. Of course, this requires the valve to be produced in large batch sizes. Economically viable production of forging dies can only be achieved by producing large quantities. Completely enclosed diaphragm During the design stage of the SISTO-C series innovative new paths were explored. A wide range of variants comprising simple straight-way valves, welded designs and complex multi-port valve manifolds means that SISTO can offer customised solutions for every type of application. “If we combined all of the possible components together, we would have at least 1 000 different variants,” Knöbl estimated. The valve series set new benchmarks with its completely enclosed diaphragm. This is crucial for the high pressure limit offered by the series. The diaphragm is inserted in a recess and seated on a small defined surface. The biggest advan- tage is that it is very robust in operation and has an increased service life compared with conventional diaphragms. “This property often influences our customers’ purchase decisions

pressures of 2 to 3 bar. InWFI supply, the pressures can reach up to 10 bar,” commented Knöbl, comparing applications. Key starting point – the material A valve for sterile applications has to do far more than steer fluids for CIP/SIP cleaning into the right direction. For over 20 years the Luxembourg-based valve manufacturer has been optimising its SISTO-C series and supplied prestigious proj- ects with this diaphragmvalve. “Around hundred thousand of these SISTO-C valves have been installed to date,” said Knöbl. The valves fulfilled the following requirements: • GMP Guidelines (Good Manufacturing Practice) • Food and Drug Administration (FDA) of the USA • United States Pharmacopeia (USP) The selected materials were very carefully tested and their production was precisely documented. To avoid cracks in the high-alloy stainless steels during orbital welding and to enable optimum machining processes, the sulphur content has to be kept within very tight tolerances. Furthermore, an optimum delta ferrite content is a key requirement in the pharmaceutical sector. Pharmaceutical valves are often

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Chemical Technology • October 2015