Back-up Rings are used in conjunction with O-Rings for both static and dynamic sealing applications. Back-up rings prevent extrusion of the o-ring when it is subjected to high pressures. Back-up rings help when the extrusion gaps are excessive. Two back-up rings should be used, one on each side of the o-ring, wherever possible. Back-up rings are washer like devices. Back-up rings are not seals themselves. Back-up rings are a support item like a spacer. Back-up rings are available in two designs, a flat washer style and a contoured style. Back-up rings may also be called buffer rings.
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