Standard and Custom O-Rings

What is an O-Ring?

An O-ring is a circular, or doughnut-shaped sealing device, generally molded from an elastomer or thermoplastic material, such as PTFE. O-rings are engineered to fit snugly into grooves and compress between two or more parts to form a seal, primarily for sealing and protecting against liquid and gas loss. These seals can also function in a wide range of temperatures and pressures.

What is an O-Ring Seal?

An O-ring seal assembly generally consists of an elastomer O-ring sitting in a sealing gland. The gland — usually cut into the metal or other rigid material of the fluid system — contains and supports the O-ring. Each of these two elements is meticulously designed and manufactured to create the best possible seal.

What are the advantages of O-Rings?

• Wide Range of Sealing Capabilities – O-rings can seal across a wide range of pressures, temperatures, media, and geometries.
• Low Maintenance – O-rings offer ease of service, requiring zero smearing or re-tightening.
• No Tightening Required – No critical torque on tightening, making them unlikely to cause structural damage.
• Lightweight & Compact Design – O-rings are lightweight and take up minimal space, making them great for applications where a compact sealing solution is needed.
• Cost Efficiency – O-rings are inexpensive to install, making them a cost-effective sealing choice for many applications.
• Reusability – They can often be reused, unlike non-elastic flat seals and crush-type gaskets.
• Long Lifespan – When used properly, the lifespan of an O-ring will match the normal aging period of the specific O-ring material.
• Failure Detection – O-rings typically fail gradually instead of all at once, making it easy to identify and address potential issues.
• Less Sensitive to Compression – Since an O-ring groove generally allows for metal-to-metal contact, they are not affected by differing amounts of compression, as with flat gaskets.

How are O-Ring sizes measured?

O-rings are measured by their internal diameter (ID), outer diameter (OD), and cross-sectional diameter (CS). These measurements are taken in inches or millimeters and are important for ensuring a correct fit and proper seal. Sealing Devices carries multiple O-ring styles, including AS568, the SAE standard. Refer to our O-ring size chart to assist you in finding the right fit.