Static seals

O-rings

The O-ring is one of the most common sealing devices and is used in the most different applications. The design is unique with its ingenious simplicity. The O-ring seals through its deformation between the surfaces against which it is supposed to seal.

O-rings are often used as static sealing elements in hydraulic systems. However, they tend to extrude into the clearance already at low pressures and are thereby destroyed. A common solution is to use O-rings of a material with increased hardness, e.g. 90° IRH. This provides a certain improvement, but a better solution for hydraulic applications is instead to combine O-rings for static functions with back-up rings.

Back-up rings

Back-up rings are intended to be used together with O-rings when the fitting clearance between the surfaces that the O-ring should seal is large enough to allow the O-ring to extrude at certain working pressures.
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