O-Rings are used to seal mechanical parts against fluid movement (air or liquid). O-Rings perform their sealing action by deforming to take the shape of their cavity, after being oversized to guarantee a predetermined interference fit. O-Rings are inserted into cavities defined as glands, and are typically used in one of two seal designs - axial or radial. An O-ring sealing system is often one of the first sealing systems considered when a fluid closure is designed because it has several advantages including simplicity, low cost, ease of installation, ease of maintenance, no adjustment required and no critical torque in clamping.
from: O-Rings Inc.
Standard O-Rings have been the designers solution in many demanding sealing applications for years. They range in size from 0.029" ID to 29" ID with cross sections from 0.030 to 0.375. Custom molded o-rings can have cross-sections as large as 0.400" and an unlimited ID without splice joints. Starndard O-Rings are made from more than 150 active proprietary compounds to ensure long-term retention of physical properties. Special-purpose materials that meet various UL (Underwriters Laboratories), NSF, USP, FDA, MIL, AMS, ASTM, and SAE line callouts are available.
O-Rings can be supplied by Gould Fasteners from these manufacturers: