Freudenberg-NOK Sealing Technologies, Plymouth, Mich., introduced washers that consist of a flat metallic gasket and a trapezoidal, vulcanized-on elastomer bead to produce excellent results in combination with standard screws in the splash zones of dairy operations.
The "Hygienic Usit" seal boasts an elastomer bead made of "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.
Hygienic Usit prevents accelerated corrosion resulting from the metabolism of microorganisms beneath a screw head, and is 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°C as well as to 2% nitric acid and 5% caustic soda at temperatures up to 80°C.
Freudenberg-NOK Sealing Technologies