O-Ring Design

There are many approaches to o-ring design, but with a little work, many of your applications can use simplified rules to speed your design process.

First, you must understand O-ring sizes, and learn what is accessible and available for you to use.  In the US, the most common o-ring standard is called Aerospace Size Standard for O-Rings (AS-568 ).  Each o-ring size is officially written as AS568-XXX, where the -XXX denoted a particular size of o-ring.  In practice, this gets shortened to simply “-XXX” and is commonly referred to as a “dash number”.

Next, understand the basics of O-Ring groove design for static sealing applications.

Finally, you can delve into o-ring design practices for dynamic sealing applications.

You will need to understand the following terms:

O-Ring Inner Diameter (ID)

0-Ring Cross Section (CS)

O-Ring Stretch

O-Ring Compression

O-Ring Percent Fill

 

O-Ring Material Selection Guide — NBR, FKM, EPDM, Silicone & PTFE Compared

by

Choosing the Right O-Ring Material The o-ring cross-section and groove are important, but the material determines whether your seal actually works in your application. Temperature, chemical exposure, pressure, and dynamic vs. static service all influence material choice. Material Comparison Table Property Nitrile (NBR) Viton (FKM) EPDM Silicone PTFE (Teflon) Neoprene (CR) Temp Range (°F) -40 … Read more

400 Series Standard O-Ring Sizes 350–439 (AS568)

by

400 Series — Cross-Section: 0.275″ This table lists all standard o-ring sizes in the AS568 400 series (dash numbers 350–439). All o-rings in this series have a cross-section diameter of 0.275″. The inner diameter (ID) ranges from 0.176″–26.940″. Need help designing a groove for these o-rings? See the Static O-Ring Groove Design Guide. For other … Read more

300 Series Standard O-Ring Sizes 265–349 (AS568)

by

300 Series — Cross-Section: 0.210″ This table lists all standard o-ring sizes in the AS568 300 series (dash numbers 265–349). All o-rings in this series have a cross-section diameter of 0.210″. The inner diameter (ID) ranges from 4.975″–22.940″. Need help designing a groove for these o-rings? See the Static O-Ring Groove Design Guide. For other … Read more

200 Series Standard O-Ring Sizes 201–264 (AS568)

by

200 Series — Cross-Section: 0.139″ This table lists all standard o-ring sizes in the AS568 200 series (dash numbers 201–264). All o-rings in this series have a cross-section diameter of 0.139″. The inner diameter (ID) ranges from 0.171″–16.955″. Need help designing a groove for these o-rings? See the Static O-Ring Groove Design Guide. For other … Read more

100 Series Standard O-Ring Sizes 115–178 (AS568)

by

100 Series — Cross-Section: 0.103″ This table lists all standard o-ring sizes in the AS568 100 series (dash numbers 115–178). All o-rings in this series have a cross-section diameter of 0.103″. The inner diameter (ID) ranges from 0.487″–11.196″. Need help designing a groove for these o-rings? See the Static O-Ring Groove Design Guide. For other … Read more

000 Series Standard O-Ring Sizes 001–114 (AS568)

by

000 Series — Cross-Section: 0.070″ This table lists all standard o-ring sizes in the AS568 000 series (dash numbers 001–114). All o-rings in this series have a cross-section diameter of 0.070″. The inner diameter (ID) ranges from 0.029″–5.234″. Need help designing a groove for these o-rings? See the Static O-Ring Groove Design Guide. For other … Read more