Seal Glossary

A doughnut-shaped object, or torus, that functions as a seal blocking the passage of liquids or gases. This seal is energized by being compressed between two mating surfaces comprising the walls of the cavity (gland).

A washer-like device of a relatively hard, tough material installed in the gland on the downstream side of the o-ring to prevent o-ring extrusion into the diametrical gap while under pressure.

Used extensively throughout the pneumatic and hydraulic industries because of low breakaway force and dynamic friction. Also used for sealing large extrusion gaps. Designed for low speeds/pressures and can be energized with springs or o-rings.

Designed to exclude foreign debris from contaminating the sealed system via a long, flexible lip. Should not be considered as the primary seal, only as a secondary seal.

Typically employed in engines, pumps, and electric motors. Maximum RPM for effective sealing depends on many factors such as surface speed, shaft finish and hardness, pressure, eccentricity, and lubrication.

An alternative to flat gaskets and other gasketing methods for sealing plastic or metal housings. Features round “o-ring” cross section and can be reused after disassembly.

Combination of elastomer and fabric that operates as both a seal and a filter.

A seal combining the structural advantages of metal or plastic with the sealing advantages of elastomers.

A four-lobed profile primarily used in dynamic situations because of reduced friction and increased resistance to spiral failure. The parting line is located away from the sealing surface, unlike o-rings in radial applications.

A set of elastomeric and sometimes non-elastomeric rings which rely on fluid pressure to activate the seal. Primarily used in dynamic applications such as reciprocating shafts.