O-Ring Standards Introduction | AS568, ISO 3601, DIN 3771 & BS Series Guide

Introduction

O-rings are the most widely used sealing components in engineering. To ensure compatibility and reliability, O-rings are produced according to international standards that define sizes, tolerances, and materials.

Common O-Ring Standards

• AS568 (USA Standard): Inch-based O-ring sizes, commonly used in aerospace, automotive, and hydraulic systems.

• ISO 3601 (International Standard): Metric sizes and tolerances, widely adopted across industries for global interchangeability.

• DIN 3771 (German Standard): Metric-based O-rings, frequently used in European industrial and hydraulic applications.

• BS 1806 & BS 4518 (British Standards): Inch and metric standards, often found in older systems and specialized industries.

Applications