Rotary seals come in many profiles with a variety of lip configurations. Some applications may only require one lip while others may require multiple sealing lips. Some even require multiple sealing lips with a “dust” lip to prevent dirt, dust, or fluid from entering the cylinder itself.
Rotary seals can have a metal outer case (called a “can”) or a nonmetallic outer case, such as in the Parker JM Clipper seal. Metal cased rotary seals might have a rubber jacket to assist in the sealing on the outside diameter. Some rotary seals have no case at all, such as the V-seal. You will also find rotary seals with garter springs. Garter springs are used to provide a constant load on the sealing lip.
Mechanical seals, bearing isolators, and cartridge seals are also types of rotary seals. Most commonly found in pumps and mixers, mechanical seals have one rotating face and one static face. All mechanical seals are fitted with an O-ring.