Freudenberg developed the “Hygienic Usit” to prevent this. It has an elastomer bead made of the high-performance material “70 EPDM 291,” 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 already meet the hygienic requirements with far more cost-effective polished standard screws, based on the current standards of the food industry.
The Hygienic Usit seal ring is a further development of the metallic ring seals used in machine-building. They seal static machine parts against liquid and gaseous media in a straightforward, economical way. 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 vapor at temperatures up to 180 degrees Celsius as well as to 2% nitric acid and 5% caustic soda at temperatures up to 80°C. The Hygienic Usit from Freudenberg thus meets the highest possible standards for the concentrations and temperatures that are recommended by producers of cleaning agents.