ABSTRACT
Large numbers of different elastomeric seal designs are applied in duties involving sealing between parts with little or no relative motion. The most familiar of these is the O-ring seal. In dynamic seals too, O-rings are widely used, as secondary seals. The “automatic” sealing mechanism of an elastomeric seal relies on the elasticity and incompressibility of the elastomer material, and the existence of an initial “interference” or “preload.” An O-ring’s contact width gradually diminishes to zero as the fluid pressure becomes very high. This behavior can be understood by considering what happens if the O-ring is compressed by pressure in a free state. In principle, O-rings can be installed so that they are either compressed axially between flanges or radially between cylindrical surfaces. At high pressure, precautions are necessary to avoid damage to the O-ring due to extrusion into the gap at the low-pressure end of the O-ring groove.
