Introduced originally in 1958 as ARP568 “Uniform Dash Numbering System for O-Rings” with a combination of ID and Cross-Sectional measurements and tolerances to identify standard sized O-Rings. The AS568 Size and Tolerance chart has been widely used commercially and is in process of being incorporated into all U.S. Military specifications and drawings.
Last revised in 2001 as the AS568B Specification, this revision simplified some tolerances and provided an improved description of how to utilize. The AS568B standard was adopted by the U.S. Department of Defense in 2005 and is expected to be used in future military specifications and incorporated into older ones.
AS568B size chart encompasses 5 different Cross-Sectional sizes and ID measurements from 1/32″ to over 26″ to provide a wide range of sizes that can be utilized in commercial, automotive, heavy duty transportation and industrial applications.
In Addition, 20 boss tube O-Ring sizes are included to provide a range of standard O-Ring sizes for straight thread tube fittings on a boss.
McMasters Koss has supplied O-Rings to automotive manufacturers worldwide meeting the AS568B specification and has inspection teams trained and equipment calibrated to validate conformance of many commercial and Automotive Level 3 PPAP O-Rings.
Please click here to download the pdf version of McMasters Koss AS568 Size chart and contact our sales engineering team for any assistance with your new design or replacement seal application.