A Technical Guide to Choosing O-Rings

TECHSiL are proud to be a preferred distributer of Trelleborg Sealing Solutions for O-Rings and Bonded Seals. Specifying the right o-ring seal can be difficult because there are many different conditions to be considered. 

Material selection

• Application parameters
• Medium to be sealed
• Working temperature
• Working pressure
• Type of use (dynamic, static)
• Necessary physical and mechanical properties E.g. hardness
• Applicable standards or approvals (e.g. defence standards and institutional approvals for drinking water application)

Housing layout, groove layout and O-Ring size

• Method of O-Ring installation/type of use - Axial (static) or Radial (dynamic or static)
• Groove design
• Groove width
• Groove/housing height
• Rounded edges and lead-in chamfers for easier installation
• Radial clearance (sealing gap)
• Surface finish of the groove diameter, groove flanks and the mating surface
• Initial compression of the O-Ring
• Elongation – outside diameter interference of the O-Ring; Groove fill; Tolerances

O-Ring Quality

• Dimensional tolerances - Inside diameter, Cross section ISO 3601-1 is recommended
• Surface quality - ISO 3601-3 is recommended
• Applicable standards

Correct O-Ring installation

• Level of stretching
• Speed of stretching
• Design of assembly tool
• O-Ring twisting – Lubrication, Assembly tools
• O-Ring damage - Use of assembly tools, Design of assembly tool

For further assistance on selecting the right O-Rings, speak to our Technical Team.