Outline shape of a contact seal. Corresponding to the wide-ranging requirements there are numerous profile shapes that almost all have a sealing edge as a common feature. (Exception, e.g., sealing ring)
The sealing profile is generally shaped or dimensioned such that it deforms on installation in the sealing space and as a consequence produces a preload that is the prerequisite for the initiation of the sealing action. On elastomer seals this preload is increased in proportion to the fluid pressure (automatic sealing).