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O-rings are one of the most popular types of seal as they are simple, effective, widely available and easily installed. O-Ring sizes are specified by their inside diameter (ID) and cross-section (CS). Metric O-Ring cross sections are actual sizes, however imperial o-ring cross sections are nominal sizes. The sealing performance of O-rings are determined by the extrusion gap, groove dimensions, surface finishes and the O-ring material. Also ask us about our range of backup washers to improve the extrusion resistance of O-rings.


O-rings are available in a wide range of materials and sizes, making them compatible with almost any static and dynamic application imaginable.

Brand advantage

MHS Seals stock and supply from the most reputable manufacturers worldwide, with many offering material certification. By selecting the best products from each of our suppliers, we can offer an enormous range of seals that are of the highest quality and you can be confident that your equipment will perform efficiently and reliably year after year. We are also able to custom manufacture seals to meet your needs. Contact one of our technicians and we will provide you with a superior seal solution.

Technical information

The O-ring material is critical to the effectiveness of the seal, which can affect the performance and reliability of the machinery. Each type of elastomer is compatible with a different range of operating conditions such as pressures, temperatures, type of media present, and whether it is a static or dynamic seal.

These are the most common o-ring materials we supply:

Nitrile (Buna N)N7 70 Durometer
N9 90 Durometer
-40°C to +110°C
Viton (Fluorocarbon)V7 75 Durometer
V9 90 Durometer
-35°C to +205°C
Neoprene (Chloroprene)C7 70 Durometer-55°C to +140°C
Ethylene Propylene (EPDM)E7 70 Durometer-55°C to +150°C
SiliconeS7 70 Durometer-85°C to +230°C

MHS Seals can also provide o-rings in PTFE, Urethane, Kalrez, HNBR, and TFEV.

Standard sizing options are included in the Seal product catalogue, available for download. You may also like to download our poster sized O-ring failure guide.

Storage tip

Storage conditions are much more important than age in determining the useful life of elastomeric seals, especially in harsh environments. O-rings are affected by contamination, harsh light, oxygen and ozone, as well as being stored while stretched. To maximise the shelf life of O-rings they should be protected from air and light, and should not be stretched while stored.