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An O-ring is a torus – a doughnut shaped ring – generally molded from an elastomer. The simplicity of the shape of an O-ring and the reliability of its function is ingenious and that is why they are the most frequently used type of seal. They are economical to manufacture and easy to fit – that makes them unbeatable.

The advantages of O-rings are:

  • they work over a wide range of pressure temperature and tolerances
  • ease of service – no smearing or re-tightening
  • no critical torque on tightening so they’re unlikely to cause structural damage
  • o-rings require very little space and are light in weight
  • the duration of life in the correct application corresponds to the normal ageing period of the O-ring material.

O-ring elastomers

The base polymer of an elastomeric compound is called rubber. That may be a natural rubber or, more commonly today, a synthetic rubber.

An elastomeric compound typically contains 50-60% of a base polymer with the remainder consisting of various fillers, vulcanising agents, accelerators, ageing retardants and other chemicals that modify the physical properties of the base polymer to suit specific applications.

O-rings are available in the following compounds:

  • Nitrile 70 & 90 Durometer
  • Viton® 75 & 90 Durometer
  • Neoprene
  • EPDM
  • Silicone
  • Fluorosilicone
  • PTFE
  • FEP Encapsulated Viton & Silicone
  • Aflas®
  • Kalrez® – perfluoroelastomer