Major O-ring manufacturers follow the AS568B standard for maintaining standard sizes in their inventory. These sizes in Aerospace Standard (AS568B) given by the Society of Automotive Engineers are defined by dash numbers. Each dash number corresponds to a fixed size.

British Standard or BS standard includes all sizes in AS568 with some other additions. BS 1806 O ring size standard was issued by British Standard Institution and has a list of all Imperial size standards. Though this has been superseded by BS ISO 3601, it is still relevant in today’s time as it is widely referenced in the European region.

The Japanese Industrial Standard ( JIS B2401) are categorized in to 3 groups, namely, Aerospace Group, General Purpose Group and Traditional Group. These O rings are used in Japans’s Automotive, semi-conductor, heavy engineering and other allied industries. The JIS B2401 follow ISO 3601-1 very closely with a few extra sizes.

Standard metric sizes for O-rings are defined by the International Standard ISO 3601-1:2002: Fluid power systems O-rings Part 1. These sizes are grouped into 2 series; G and A. G series is preferred for general applications and A series is recommended for Aerospace or any other critical application requiring sharp tolerances.

PTFE O-RINGS

PTFE encapsulated O-rings, also known as FEP encapsulated and PFA encapsulated o-rings, are Vitoria or Silicone O-rings encapsulated within a PTFE jacket These o-rings hence offer an ideal combination of the unique properties of vitons/siiicone as well as PTFE. They outperform the conventional o-rings in harsh environments owing to their excellent chemical resistance, temperature resistance and mechanical properties. Depending on the core material i.e. Viton° or Silicone, they are suited for operating in temperatures ranging from -62° to 204°C (-80° to +400° F)

X-RINGS

X-Rings, also known as quad rings, are a hybrid design of an O ring and a square ring. Compared to o-rings, which have a single lobed design, x-rings come with a four-lobed design. X-rings offer twice the sealing surface in comparison to a standard o-ring. Due to this double sealing function, x-rings provide a double sealing function and can be used in a variety of static as well as dynamic sealing applications. The double-seal action requires less squeeze to maintain an effective seal. This reduction in squeeze in turn means less friction and improved seal life.