O-rings is one of the most common seals in use today. They can be used in both static and dynamic applications and offer an economic and effective sealing solution. By choosing a compound and hardness it is usually possible to find a suitable O-ring for most applications. Rubber O-rings can operate in temperatures from -55 deg C to + 320 deg C and (with backup rings) at pressures of 400 Bar. They are available in a large range of standard imperial and metric sizes The most common international standards for O-Ring dimensions, in addition to ISO 3601/1 are:-

• American Standard : AS-568
• Great Britain : BS 1806 – BS 4518,
• Germany: DIN 3771,
• France: NF T 47 501,
• Japan: JIS B 2401-77

• Common metric sections include 1.0mm, 1.5mm, 2.0mm, 2.5mm 3.0mm, 3,5mm, 4.0mm, 4.5mm 5.0mm, 6.0 etc.
• Common Swedish sections include 1.6mm, 2.4mm, 5.7mm, 8.4mm
• Common French sections include 1.8mm
• Common Japanese Sections include 1.9mm, 2.7mm, 3.1mm 3.6mm,
• Common Imperial sections are 1.78mm, 2.62mm, 3.53mm, 5.33mm and 6.99mm

It can be seen from the above that there is an o ring section to suit almost any requirement, inside dimensions range from less than 1mm to over 800 mm with bigger sizes than that available as Customer Specials “.

Common rubber compounds are available in a range of hardness grades, the most common being 70 shore (Standard Hardness), 80 shore, 90 shore (Hard) is also available, with 40/50 shore (soft) being the least popular. Fluoro elastomer (VITON) O’rings to be slightly harder with 75/80 Shore being the norm.