Sealing technology manual for the process industry - PTFE U-packings

PTFE U-PACKINGS U-packings are unidirectional sealing elements with a U-shaped cross-section and a reinforcing metal spring which are used for sealing applications involving rotary or translatory motion. PTFE U-packings are sealing components that enjoy a wide range of uses in the food and beverage industry, from ball valves to piston pumps. They are ideal for the sealing of pressures, as the system pressure amplifies their sealing function, as well as for aggressive media, thanks to PTFE’s excellent media resistance. PTFE U-packings contain a metal spring, which compen- sates for the loss of initial load caused by PTFE’s tendency to creep. The contact pressure can be tailored to the param- eters of the individual application scenario by means of u-, v- or o-shaped springs – open or crimped. PTFE U-packings are available as axial or radial sealing models for sealing ap- plications involving translatory or rotary motion. Radial seal- ing models are available in inside and outside sealing ver- sions. Function • Sealing of rotary and translatory motions • Sealing of aggressive media and pressures Dimensions • Manufactured by machining, therefore available in nearly all dimensions • Springs to match the dimensions are manufactured from endless material • Standard dimensions (see types) available in stock Installation and assembly • Installation preferably without stretching or compressing of the rings. If stretching or compression is unavoidable, please consult Freudenberg. Lightly oil the rings prior to installation • Please refer to page 94 for general installation and assem- bly instructions Applications • Ball valves • Flanges and lids • Swivel joints • Distribution manifolds • Hot water and steam valves • Fittings • Piston pumps • Bearings TYPES Axial sealing • Variants with dynamic internal sealing lip for use as a rod seal: standard rod diameters from 10 to 200 mm • Variants with external sealing lip for use as a piston seal: standard piston diameters from 15 to 200 mm Radial sealing • With inward sealing function for use as a pressure seal (dimensions on request) • With outward sealing function for use as a vacuum seal (dimensions on request) Spring types • V-springs with a great degree of spring travel and soft spring characteristic for reduced friction, can be used for dynamic and static sealing and for rotation sealing • U-spring with a great degree of spring travel and hig- her spring rate for sealing of higher pressures • Round springs for high spring force with a lower de- gree of spring travel for sealing of extremely high pressures. Its special design distributes the spring load over a number of different sealing lips Material variants • Pure PTFE • PTFE with glass fibers • PTFE with carbon • PTFE with carbon fibers • PTFE with glass and/or molybdenum • PTFE with Ekonol • PTFE with aramid • UHMW PE (polyethylene) • PEEK APPENDIX PRODUCT PORTFOLIO MATERIALS RESISTANCE & PURITY ENGINEERING PLASTICS ELASTOMERIC MATERIALS TECHNICAL FUNDAMENTALS INTRODUCTION 89

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