Key Takeaways
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The Society of Automotive Engineers (SAE) AS568 standard and International Organization for Standardization (ISO) 3601 define the most widely used O-ring dimensional and tolerance specifications.
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Food and Drug Administration (FDA) approval and National Sanitation Foundation (NSF) certification are required for O-rings used in food, beverage, pharmaceutical, and drinking water applications.
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American Society for Testing and Materials (ASTM), Underwriters Laboratories (UL), Aerospace Material Specification (AMS), and military specification (Mil-Spec) standards apply to O-rings in specialized industries.
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Chemical compatibility, temperature ratings, and pressure ratings must be confirmed for the specific fluid and operating environment before selecting an O-ring material.
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Manufacturers certified to ISO 9001 or International Automotive Task Force (IATF) 16949 quality management standards demonstrate a commitment to consistent O-ring quality.
When selecting O-rings for specific applications, awareness of industry standards and certifications ensures optimal performance, safety, and reliability. The following eleven standards and certification categories are the most important to understand when specifying O-rings.
What Are the Key O-Ring Industry Standards and Certifications?
1. AS568 (SAE Standard)
The AS568 standard, established by the Society of Automotive Engineers (SAE), defines the dimensions and tolerances of O-rings. This is the most widely referenced standard for O-ring sizing in North American applications.
2. ISO 3601 (ISO Standard)
The International Organization for Standardization (ISO) has its own standard for O-rings, known as ISO 3601. This standard covers O-ring dimensions, tolerances, and material specifications and is widely used in international applications.
3. FDA Approval
Food and Drug Administration (FDA) approval is required for O-rings used in applications involving contact with food, beverages, pharmaceuticals, or medical devices. FDA-compliant materials must meet 21 CFR (Code of Federal Regulations) requirements for safe food contact.
4. NSF Certification
The National Sanitation Foundation (NSF) provides certification for materials that are safe for use in drinking water and food-related applications. NSF 61 certification is commonly required for O-rings in potable water systems.
5. ASTM Standard
Published by the American Society for Testing and Materials (ASTM), this standard provides guidance on the classification of rubber products, including O-ring materials. ASTM D2000 is the primary classification system for rubber compounds used in O-rings.
6. UL Recognition
Underwriters Laboratories (UL) recognition applies to O-rings used in electronics and electrical applications. UL-recognized materials have been evaluated for compliance with applicable safety standards for electrical insulation and component use.
7. AMS Specifications
Aerospace Material Specification (AMS) standards govern O-ring materials and dimensions for aerospace applications. These specifications are issued by SAE International and define the performance requirements for O-rings in aircraft and spacecraft systems.
8. Mil-Spec Standards
Military specification (Mil-Spec) standards define O-ring requirements for military and defense applications. These standards ensure that O-rings meet the stringent performance, dimensional, and material requirements of defense procurement.
9. Chemical Compatibility
O-ring material selection must account for compatibility with the specific fluids, chemicals, or gases present in the application. Incompatible materials degrade rapidly, leading to seal failure. Verify chemical compatibility data for the selected compound and fluid system before specifying an O-ring.
10. Temperature and Pressure Ratings
O-rings must be rated for the operating temperature range and pressure conditions of the application. Material selection directly affects the upper and lower temperature limits and the pressure capacity of the seal.
11. ISO 9001 / IATF 16949 (Quality Management)
Manufacturers that adhere to quality management systems such as ISO 9001 or International Automotive Task Force (IATF) 16949 demonstrate a commitment to consistent quality in O-ring production. Certification to these standards indicates that manufacturing processes are controlled and audited for compliance.
For additional guidance on O-ring selection, see Your Guide to O-Ring Types and Selecting the Right Type of O-Ring for Your Application.
Need Help Selecting the Right O-Ring?
Contact us today or call us at 800-669-9650 for help with your O-ring needs. We have 11 locations across the Southeast and Midwest, including Knoxville, TN; Marietta, GA; Orlando, FL; Charlotte, NC; Little Rock, AR; Fort Worth, TX; Benton, IL; Madisonville, KY; Princeton, WV; Birmingham, AL; and Calvert City, KY.
Frequently Asked Questions About O-Ring Industry Standards
The AS568 standard, established by the Society of Automotive Engineers (SAE), defines the standardized sizes, dimensions, and tolerances for O-rings used in North American applications. It is the most widely referenced O-ring sizing standard in the United States.
Yes. O-rings that come into contact with food, beverages, pharmaceuticals, or medical devices must use materials that meet Food and Drug Administration (FDA) requirements under 21 CFR. The O-ring compound must be FDA-compliant for the specific contact type and temperature range involved.
Both AS568 and ISO 3601 define O-ring dimensions and tolerances, but they use different sizing systems. AS568 is the predominant standard in North American applications, while ISO 3601 is the international standard used in European and global markets. Some sizes are equivalent between the two systems; others differ.
Aerospace applications are governed by Aerospace Material Specification (AMS) standards issued by SAE International. These define the material composition, dimensional requirements, and performance characteristics for O-rings used in aircraft and spacecraft systems.
The required certification depends on the application. Food and beverage contact applications require FDA-compliant materials and may require National Sanitation Foundation (NSF) 61 certification for potable water. Aerospace applications use AMS specifications. Electrical applications may require Underwriters Laboratories (UL) recognition. Military and defense applications use Mil-Spec standards. Contact Royal Brass and Hose for guidance on certification requirements for your specific application.
