An O-Ring, also known as a packing, or a toric joint, is a gasket in the shape of a torus, or doughnut shape. It is a loop of elastomer with a round cross-section, designed to be seated in a groove and/or compressed during assembly between two or more parts, creating a seal. The O-Ring may be used in static or dynamic applications where there is relative motion between the parts and the O-Ring.
O-Rings are one of the most common seals used in machine design because they are inexpensive, easy to make, and reliable and have simple mounting requirements.
They are manufactured in standard or inch sizes, and metric sizes and can be made from almost any elastomer. The most commonly used is Buna (also called nitrile). Buna is used often because of its good mechanical properties, its resistance to lubricants and greases, and its relatively low cost. Other elastomers are also used based on their resistance to certain chemicals or various high or low-temperature ranges, add a myriad of design and application factors.
Elastomers that are used most commonly used, include:
- Viton (FKM)
- EPDM (EPR)
- Silicone (SiR)
- Highly Saturated Nitrile (HSN)
- PTFE (Teflon)
- PTFE Coated (Teflon coated, usually Silicone or Viton)
- PTFE Encapsulated (Usually Silicone or Viton covered with a Teflon tube)
- Kalrez, Chemraz, Simriz (FFKM)
- Aflaz (TFE/P)
- Custom compounds and formulations
These are not the only elastomers available, but the ones used most often. Elastomers can be compounded with different properties for different chemical capabilities, high or low temperature gradients, hardness and many other factors an O-Ring may encounter during its life-cycle.
O-Rings and related categories include:
Rocket Seals can also supply:
- AS568 (2-XXX, 3-XXX, 5-XXX Sizes)
- FDA and USP Class VI
- Mil, AMS and NAS Spec
- NSF 51, NSF 61 and UL Listed