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Freudenberg-NOK seals combat corrosion and bacteria in the food industry

Open processes put especially high hygienic demands on the food and beverage industry, since they function in facilities that are not closed off from the environment and thus need to be cleaned and sterilised regularly.

Freudenberg-NOK has introduced seals that consist of a flat metallic gasket and a trapezoidal, vulcanised-on elastomer bead that produce good results in combination with standard screws in the splash zones of dairy operations. 

Milk is a valuable yet sensitive raw material from which a whole series of other foods are produced, including cheese, cream, and yogurt.

Depending on the size of the facility, several hundred screw connections come into use in production equipment, stirring devices, and containers, and they can be potential entry points for impurities and bacteria.

So-called dead space can result between screw heads and the washers as well as the housing and the washers, and microorganisms can become established there.

In these situations, the gaps function as capillary spaces and actually draw fluids in.

If bacteria and germs settle there, it is impossible to remove them from the gap from the exterior.

This reduces the stability of dairy products and in the worst case can result in the destruction of entire batches.

Freudenberg-NOK developed the Hygienic Usit seal to prevent this situation.

The new seals has an elastomer bead made of the high-performance ‘70 EPDM 291’ material, creating a dead-space-free, static seal and making it impossible for microfilms to form between the screw head and the contact surface.

In areas with product contact, such as at the screw connections for stirrer blades, the seals are used in combination with special polished screws, which greatly eases cleaning.

But there are other areas where Hygienic Usit seals meet the hygienic requirements with more cost-effective polished standard screws, based on the current standards of the food industry.

These areas include the splash zones in dairies, where the Hygienic Usit prevents accelerated corrosion resulting from the metabolism of microorganisms beneath a screw head, for example, for the mounting feet of machinery or frame screws.

Fast-advancing corrosion in areas that cannot be viewed from the outside can be ruled out with the help of Hygienic Usit seals.

The Hygienic Usit seal ring is a further development of the metallic ring seals used in machine-building and they seal static machine parts against liquid and gaseous media in an economical way.

The special recipe for the sealing material ensures that the requirements of European and American food industries are met.

In addition, there is now a US Department of Agriculture certificate available especially for the dairy industry.  

The material is also resistant to the cleaning procedures used in open processes, in which facilities are completely cleaned from the exterior.

Among other things, this includes resistance to water vapour at temperatures up to 180°C as well as to 2% nitric acid and 5% caustic soda at temperatures up to 80°C.

The Hygienic Usit thus meets the highest standards for the concentrations and temperatures that are recommended by cleaning agent producers.