Contact seals

Contact seals (fig. 1) are generally very reliable. Their effectiveness, however, depends on a number of factors including:
  • the seal design
  • the seal material
  • the contact pressure
  • the surface finish of the seal counterface
  • the condition of the seal lip
  • the presence of lubricant between the seal lip and counterface
The contact pressure (fig. 1) can be produced either by:
  • the resilience of the seal, resulting from the elastic properties of the seal material (a)
  • the designed interference between the seal and its counterface (b)
  • a force exerted by a garter spring incorporated in the seal (c)
Friction between the seal lip and counterface can generate a significant amount of heat. As a result, these seals have circumferential speed limits. They are also susceptible to mechanical damage as a result of improper mounting, or by solid contaminants. To protect the seal from the damage caused by solid contaminants, a non-contact seal is typically placed in front of a contact seal.
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