What is an O-ring?

An O-ring is a torus, or doughnut-shaped ring, generally molded from an elastomer, although O-rings are also made from PTFE and other thermoplastic materials, as well as metals, both hollow and solid. This handbook, however, deals entirely with elastomeric O-rings.

O-rings are used primarily for sealing. The various types of O-ring seals are described in the section called “Scope of O-ring Use.” O-rings are also used as light-duty, mechanical drive belts. More information, including design criteria on O-ring drive belts and their applications can be found in the O-Ring Applications Section of the ORD 5700 O-Ring Handbook.

So what is an O-Ring Seal? An O-ring seal is used to prevent the loss of a fluid or gas. The seal assembly consists of an elastomeric O-ring and a gland. An O-ring is a circular cross-section ring molded from rubber (as shown above). The gland - usually cut into metal or another rigid material - contains and supports the O-ring. The combination of these two elements; O-ring and gland - constitute the classic O-ring seal assembly.