O-rings: general overview

O-rings are circle-section seals made of elastomeric material used to prevent gas or liquid leakage. Thanks to their simplicity and low cost, O-rings come in handy in a diverse range of sectors; they can be used in both static and dynamic sealing applications within a wide pressure and temperature range.

Two dimensions define the size of an O-ring: its inside diameter (ID) and its cross-sectional diameter (CS).

The sealing action takes place thanks to the closing of escape paths of the media (i.e. liquid or gas) by the O-ring. In order to seal elements where no pressure is present, it is necessary to provide for the required change of shape of the O-ring, so the depth of the housing groove should be smaller than the O-ring cross section. With the pressure rising, the O-ring is gradually compressed and deformed within its housing seat. The higher the pressure, the bigger the intensity with which the O-ring presses against its housing. For high pressure applications, it is recommended that the O-ring is mounted along with a support ring.

With proper grooving and material choice, the the O-ring can be used for a very long time within the rubber's temperature limits.