Back-up Rings are protective and supporting elements with no sealing function. Made from extrusion-resistant materials such as Turcon®, Zurcon®, Hi-Mod® or PEEK they usually have a rectangular cross section and are installed in a groove with an elastomer O-Ring. Due to their tight fit in the housing, Back-up Rings prevent extrusion of the pressurized elastomer sealing element into the clearance or extrusion gap.
Using Back-up Rings allows O-Rings to be utilized in higher pressure applications, where larger extrusion gaps are required and where there are reciprocating or rotating movements. They also compensate for large temperature fluctuations.