O-rings are round, mechanical gaskets used as sealing instruments. They are designed to be seated in a groove and compressed during assembly between two or more parts. O-rings are one of the most common types of seals because they’re inexpensive, reliable and have simple installations, while offering effective functionality.

O-Rings by Western Rubbers

Western Rubbers can manufacture O-rings in standard sizes as specified under BS-1806, JISB-2401, AS-568 and Metric Standards. We can also customize them to meet client specifications. We can formulate compounds for O-rings to meet USP, WRAS, FDA, EU Pharmacopoeia and other such stringent industry standards.Nearly all custom size O-rings, washers, square rings, and X-Rings in almost every material can be manufactured at Western Rubbers.

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O-Ring Size Standards

An O-Ring is one of the most common types of seals in the world. O-Rings are used in a variety of applications in industries across the globe. Because of its popularity, there is virtually an unlimited number of possible sizes that an o-ring can be manufactured in. Thus, the need for size standards which cover the most common sizes used.

**This information is only intended as a guide to identify O-Ring sizes from the various international standards. Although we believe this information to be correct, we cannot guarantee 100% accuracy with each and every standard. Therefore, we recommend referral to the actual specifications before proceeding with design work, etc. **

AS568 is the most commonly used standard in the United States for defining “inch sizes” of O-rings.
British Standards Institution lists all Imperial standard sizes. It has been superseded by BS ISO 3601.
Japanese Industrial Standard for O-ring sizes. This standard is often referred to as “Japanese Metrics.”
Standard Metric Sizes for O-rings are defined by the ISO
O-ring Failure Analysis Guide
Among the most common reasons for O-Ring failure is either incorrect groove design or improper selection of compound. By correctly identifying the reason for failure, necessary changes can be made to tend design or material and eventually lead to improved seal performance. Analyzing the cause of failure and going to the root of every problem is extremely crucial in assuring efficient seal functionality and safety.
O-ring Tolerance Calculator
All o-rings are designed with certain acceptable tolerance levels. The American Standard size chart i.e. AS568 has listed the acceptable tolerances. However, this data is not available for all size reference charts. Therefore, we have our Standard Metric Tolerance chart. You can either refer to AS586 or Western Rubbers’ Standard Metric Tolerance chart to view o-ring size tolerances.

Other types sealing rings

X Rings

Square Rings

PTFE Encapsulated O-Rings

Sponge O-Rings

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