Anti-extrusion Ring
A ring used to support a softer sealing ring and prevent it from extruding.
Back-up Ring
Anti-extrusion ring or support ring.
Bearing
See Wear Ring
Bi-directional Seal
A seal that prevents leakage from both directions.
Cold Flow
Continued deformation under stress
Composite Material
Materials made from two or more constituent materials with significantly different physical or chemical properties which remain separate and distinct on a macroscopic level within the finished structure.
Compression Set
The permanent deformation of a seal after release of a compressive load.
Copolymer
A copolymer is a polymer derived from two (or more) monomeric species.
Creep
Creep is the tendency of a solid material to slowly move or deform permanently under the influence of stresses.
Double acting Seal
A seal designed to take pressure from two sides.
Dynamic Seal
A seal designed to prevent leakage between two moving surfaces.
Elasticity
The property of a substance that enables it to change its length, volume, or shape in direct response to a force effecting such a change and to recover its original form upon the removal of the force.
Elastomer
An elastic substance occurring naturally, as natural rubber, or produced synthetically, as butyl rubber or nitrile.
Extrusion
Distortion or flow of part of a seal into an extrusion gap under pressure.
Extrusion Gap
The clearance on the low pressure side between two parts, which house the seal.
Face Seal
A seal that is compressed in a direction parallel to its axis.
Flash
Extruded material on the partially finished product formed during the molding process.
Flex Cracking
A surface cracking induced by repeated bending or flexing.
Free Height
The height of a seal in its free-state.
Friction
Friction is the force resisting the relative motion of two surfaces in contact.
Gasket
A rubber, metal, or other material, for packing a piston or placing around a joint to make it seal a fluid or gas.
Gland
A cavity into which a seal is installed. Component at the working end of a cylinder which contains seals.
Hardness
The measured resistance of a material to indention, abrasion, deformation, or machining.
Housing
A rigid component which contains a seal assembly.