Rubber O Ring

O-rings are bi-directional seals, circular in shape and cross section. O-rings are generally made of an elastomeric material, but may be made of other materials such as PTFE or metal. An O-ring seals through the deformation of the seal material by installation and media pressure to close off the gap between mating components. Higher system pressures can cause deformation through the gap, known as extrusion, resulting in seal failure. Choosing a harder seal material or installing back-up rings to support the O-ring may alleviate this problem.