Rectangular cross section. For static and dynamic use. Reciprocating and rotating movements possible. Material: PTFE. Back-up Rings are installed together with O-Rings and Quad-Ring® Seals to prevent extrusion in applications above 5 MPa / 725 psi. Available in spiral, cut, or uncut designs in unfilled PTFE, based on ISO 3601, AS 568.
Back-up rings have no intended sealing function. Instead, as their name indicates, they are protective and supporting elements made from extrusion-resistant materials which generally have a rectangular cross-section. They are installed in a groove together with an elastomer sealing element, preferably with a corresponding O-ring in static applications.
Due to the tight fit of the Back-up ring in the housing, they prevent extrusion of the pressurized elastomeric sealing element into the sealing gap. Typical application examples are: injection moulding machines, machine tools, presses, excavators, agricultural machines and valves for hydraulic circuits.
Type BU has a rectangular cross-section and is made of PTFE. It’s used both static and dynamic and reciprocating and rotating movements are both possible. On top of the BU features the BG type has a cut angle of 30° or 45° and is preferred for installations in a closed grooves where uncut back-up rings are not suitable.