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Static sealing solutions are used for applications involving no movement between the sealing component and the surface. A distinction is made between static axial seals, where sealing occurs parallel to the seal centerline, and static radial seals, where the seal centerline has a radial seal orientation. The seals most often used for this kind of application are O-rings, which are standardized in their sizes and tolerances.
Hygiene-Compliant O-Ring Designs
Hygienic Metallic Sealing With Elastomer Band
Designed in compliance with sanitary standards, the Freudenberg Sealing Technologies Hygienic Usit® with an elastomer bead is setting new purity benchmarks in the processing industry. Many manufacturers of machinery and facilities for the food and pharmaceutical industries frequently use standard Usit rings for screw connections or at the product space. But they are not EHEDG-compliant since germs or biofilms can accumulate as bacterial colony and corrosion under the screw head. As a result, a hygienically optimized design is not ensured.
These metallic flat seals with an elastomer bead made of 70 EPDM 291 (black), 70 EPDM 253815 (white) and 70 EPDM 217676 (blue) secures a dead-space-free sealing. For applications with aggressive CIP/SIP media, high temperatures while steam sterilization as well as fatty process media or flavors, Freudenberg Sealing Technologies offers another variant made of Fluoroprene® XP 45. This compound has an even bigger temperature range and is resistant against nonpolar media and flavourings.
A range of approvals confirms that the Hygienic Usit is the best choice for hygienically demanding applications in the food and beverage segment as well as the pharmaceutical industry. The approvals include FDA-conformity, EU 1935/2004 and USP Class VI (121 °C), plus a recommendation from the Research Center Weihenstephan for Brewing and Food Quality (testing based on the EHEDG cleanability method). It is available in standard sizes: M4, M5, M6, M8, M10, M12 and M16.
For applications with direct media contact in open and closed processes in splash zones, Freudenberg Sealing Technologies offers in cooperation with the HEINRICH KIPP WERK, Usit rings that include special hygienic screws and cap nuts optimized for their geometry and surface quality.
The screws and cap nuts with lip are polished and achieve a roughness depth as fine as Ra 0.8 µm. This unique surface neither has the pitting nor burr that would preclude a hygienic design. The patented screws and cap nuts are available in sizes M4 to M16.