What Can You Tell Me about O-Ring Structure?

Standard O-Rings and Metric O-Rings are typically described by their Internal Diameter (ID), Radial Cross Section (CS), Rubber Material from which they are constructed plus the material Hardness on a Shore A scale or Columbia Compound Number.

For AS568A Size O-Rings, parts are described as the AS568 size with a suffix of the Rubber Material from which they are constructed plus the material Hardness on a Shore A scale.  In other words, a 2-021-Buna-70 would be 021 from the AS568A sizing. This is a 1/16” Cross Section, 15/16” ID (Inside Diameter), 1 1/16” OD (Outside Diameter), made from Buna (Nitrile) and is a 70 Hardness on the Shore A scale.

For Metric Size O-Rings, parts are describes as the Cross Section, by the ID (Inside Diameter), with a suffix of the Rubber Material from which they are constructed plus the material Hardness on a Shore A scale, and in the case of some materials, the color. In other words, 2MMX21MM-FKM75-BL. This is a 2MM Cross Sections, 21MM ID (Inside Diameter), 25MM OD (Outside Diameter), made from FKM, is a 75 Hardness on the Shore A scale and is Black.

Other materials may be EPR, Silicone, PTFE, PTFE Encapsulated, PTFE Coated, Kalrez, Neoprene, HSN or HNBR (Highly Saturated Nitrile), Chemraz, Fluorosilicone and others. Different materials are suited for different jobs with considerations for fluid it comes in contact with, temperature, pressure and more.

If we can help you in any way, feel free to contact us at Rocket Seals at sales@rocketsseals.com or call 1 (800) 445-7803. If you want to order any of our products you can do it 24/7 on our website (rocketsseals.com) or call any of our staff during business hours.