BS 4518:1982+A2:2014

This standard BS 4518:1982+A2:2014 Specification for metric dimensions of toroidal sealing rings ('O'-rings) and their housings is classified in these ICS categories:

• 21.180 Housings, enclosures, other machine parts
• 21.140 Seals, glands

This British Standard specifies the dimensions of elastomeric “O”-rings which are toroidal in shape and which are used for sealing components against ingress or egress of fluids under dynamic and static conditions.

The standard also specifies the shape and dimensions of five types of associated housing grooves for the rings when used at pressures not normally exceeding 100 bar¹).

NOTE At pressures exceeding 100 bar, or when the diametral clearances of the grooves are in excess of those specified in this standard, it is recommended that these “O”-rings should be used in conjunction with anti-extrusion back-up rings. Spiral anti-extrusion back-up rings and their housings, the dimensions of which are specified in BS 5106, are suitable for pressures up to approximately 200 bar.

Two charts are provided in Appendix A to aid the selection of “O”-rings.

Dimensions and tolerances of toroidal sealing rings for hydraulic and pneumatic applications in static and dynamic situations. Also the appropriate housing dimensions when at pressures up to 100 bar.