O-rings are designed to seat in a groove and to be compressed during assembly by two or more parts, creating a seal.

Additional Information

SKU: O-RINGS Category: Tags: , ,


An O-ring is usually a circular elastomer with a disc shaped cross section. O-rings are designed to seat in a groove and to be compressed during assembly by two or more parts, creating a seal.

O-rings are generally used in either static or dynamic applications.
O-rings are measured by measuring the inside diameter of the o-ring and the cross-sectional thickness.
O-rings are available in various elastomers. Listed below are the more readily available elastomers on the market:

  • Nitrile: abbreviation:-NBR.
    At temperatures up to 100C, or with special compounding up to 120C, nitrile rubber provides an economic material having a high resistance to aliphatic hydrocarbon oils and fuels. Nitrile o-rings are available in 70, 80 and 90 shore hardness.
  • Viton®: abbreviation:-FKM.
    This is a family of rubbers designed for very high temperature operation. They can operate continuously somewhat in excess of 200C depending on the grade, and intermittently to temperatures as high as 300C. They have outstanding resistance to chemical attack by oxidation, by acids and by fuels. They have good oil resistance. Viton o-rings usually have a shore hardness of 80.
  • Silicone Rubber: abbreviation:- MVQ,FMQ,PMQ.
    The outstanding property of these materials is their very wide temperature range. Typically the range is -60C to 200C and above, with PMQ down to -90C. Silicon o-rings usually have a shore hardness of 60.
  • Ethylene Propylene Rubber: abbreviation :- EPDM
    Probably the most water resistant rubber available, and this resistance is maintained to high temperatures (up to 180C in steam for peroxide cures). EPDM rubber is also the ideal material for brake fluid, it usually comes in a shore hardness of 70.

NB : We also supply backup rings for o-rings and Quad rings.


O-rings are usually supplied in the following Metric and Imperial cross sections:
METRIC – 1mm, 1.25mm, 1.3mm, 1.5mm, 1.6mm, 2mm, 2.4mm, 2.5mm, 3mm, 4mm, 5mm, 5.7mm, 6mm ,8 and 8.4mm.
IMPERIAL – 1.78mm, 2.62mm, 3.53mm, 5.33mm and 7mm.


U-Seal can also offer you, the customer, specially moulded o-rings in standard or non-standard inside diameters, cross sectional thickness and shore hardness. We can also manufacture in other materials if you should require it. (Some other materials include: polyurethane and PTFE.)

**U-Seal also offer you machining specifications for different o-ring cross-sectional thicknesses.

**Please consult the fluid compatibility table link on our home page to choose the right elastomer for your specific requirements.