Industrial O-Rings manufactured to AS568 ISO 3601 DIN 3771 standards

O-Rings by Standard (AS568, ISO 3601, DIN 3771)

Standardized O-Rings for Global Industrial Applications

Industrial O-Rings are manufactured according to internationally recognized dimensional standards to ensure interchangeability, system compatibility, and predictable sealing performance.

We supply precision O-Rings compliant with:

  • AS568 (Inch Series – United States)
  • ISO 3601 (Metric Series – International)
  • DIN 3771 (German Industrial Standard)

These standards define inside diameter (ID), cross section (CS), and tolerance ranges, enabling engineers to design sealing systems with controlled compression and sealing reliability.

Selecting the correct dimensional standard ensures global sourcing compatibility and long-term maintenance consistency.

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International O-Ring Standards Overview

AS568 inch O-Ring size chart and dash number system

AS568 O-Rings

AS568 defines inch-based O-Ring sizes primarily used in North America and global OEM production.

  • Inch dimensions
  • Dash number system (-001 to -900 series)
  • Standard tolerance specification
  • Widely adopted in hydraulic and aerospace systems

Typical Applications:

  • Hydraulic cylinders
  • Pumps & valves
  • Aerospace assemblies
  • Industrial automation systems
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ISO 3601 metric O-Ring dimensional standard diagram

ISO 3601 O-Rings

ISO 3601 defines metric O-Ring dimensions and tolerance classes for international manufacturing.

  • Metric sizing system
  • Defined tolerance grades
  • Includes groove design guidance
  • Suitable for global supply chains

Applications:

  • European machinery
  • Automotive systems
  • Pneumatic equipment
  • Process industries
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DIN 3771 metric O-Ring dimensional specification

DIN 3771 O-Rings

DIN 3771 is a German industrial dimensional standard historically used in mechanical engineering.

  • Metric dimensions
  • Defined tolerance control
  • Common in German-designed equipment
  • DIN sizes often align with ISO metric sizes but must be verified during engineering validation.
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How to Select the Correct O-Ring Standard

O-Ring selection logic flowchart based on equipment origin, groove design, and maintenance strategy
  • Equipment Origin: US-designed systems → AS568; European systems → ISO 3601 / DIN 3771; Global distribution → ISO 3601 preferred.
  • Groove Design Specification: O-Ring performance depends on proper groove design and compression ratio. O-Ring Design Guide | Groove Design Guide
  • Maintenance & Supply Strategy: Standardization simplifies replacement sourcing, spare part inventory, and cross-border procurement.

Engineering Performance Considerations

O-Ring standards define dimensions only. Sealing performance depends on material selection and operating conditions.

Temperature Range (Typical by Material)

Comparison chart of O-Ring material temperature ranges (NBR, FKM, EPDM, FFKM)
  • NBR: -40°C to +120°C
  • FKM: -20°C to +200°C
  • EPDM: -50°C to +150°C
  • FFKM: Up to +260°C

Pressure Conditions

O-Ring compression and groove sealing diagram
  • Static sealing: up to 5,000 psi (with proper groove design)
  • Dynamic sealing: lower pressure limits recommended
  • Backup rings required above 1,500 psi (Learn about Backup Rings)

Media Compatibility

  • Petroleum oils → NBR / FKM
  • Steam & hot water → EPDM
  • Aggressive chemicals → FKM / FFKM
  • Gas sealing → low permeability compounds

For detailed material properties, visit: O-Ring Material Properties

Applications by Industry

Hydraulic cylinder application icon

Hydraulic & Pneumatic Systems

Oil refinery application icon

Oil & Gas Equipment

Automotive engine application icon

Automotive & EV Systems

Food processing line application icon

Food Processing Machinery

Chemical reactor application icon

Chemical Processing Equipment

Pneumatic valve application icon

Industrial Automation

Explore more applications: O-Rings by Application

Quality & Manufacturing Control

O-Ring dimensional inspection and hardness testing

Our manufacturing control includes:

  • Dimensional inspection
  • Hardness testing (Shore A)
  • Batch traceability
  • Visual defect screening
  • Material certification on request
O-Ring material certification and compliance

Available compliance:

  • FDA compounds
  • RoHS & REACH compliance
  • Custom compound validation

Learn more about our quality processes: Quality Certifications | Manufacturing Capabilities

Custom & Non-Standard O-Rings

Custom molded non-standard large diameter O-Rings

In addition to AS568, ISO 3601, and DIN 3771 sizes, we manufacture:

  • Non-standard metric O-Rings
  • Large diameter O-Rings
  • Custom cross sections
  • Special compounds for extreme environments
  • Color-coded O-Rings

For unique sealing challenges, explore our Custom O-Rings solutions.

Frequently Asked Questions

Q1: What is the difference between AS568 and ISO 3601?

AS568 uses inch dimensions and dash numbers. ISO 3601 defines metric sizes and tolerance grades.

Q2: Are DIN 3771 and ISO 3601 interchangeable?

Some sizes overlap, but tolerance verification is required before substitution.

Q3: Do these standards define material?

No. They define dimensions only. Material selection depends on temperature, pressure, and media.

Q4: Can you manufacture non-standard sizes?

Yes. Custom molded and vulcanized O-Rings are available based on drawings or samples.

Request a Quote for Standard O-Rings

To receive a quotation, please provide:

  • Standard (AS568 / ISO 3601 / DIN 3771)
  • Size or dash number
  • Material specification
  • Operating temperature
  • Pressure range
  • Annual demand
Request a Quote →
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