The o-ring is the most widely used seal in the industry. It is easy to install, may be used as a double-acting seal and can seal pressures up to 3000 PSI. With pressures over 800 PSI, back-up rings should be considered, depending on the operating conditions and gland design.
The o-ring is typically used in static and reciprocating applications. The o-ring is not recommended for rotary applications as the o-ring will rotate with the shaft and cause a leak (lip seals are recommended for rotary applications). O-rings are typically sized by their inside diameter and cross section, and are further specified by the type of compound and durometer hardness which best suits the application. For O-ring sizes other than standard sizes, specify the actual dimensions desired for the inside diameter (I.D.) and the cross section (W). There may be a tooling charge for such non-standards
0-rings are available in 349 sizes as set up by the Aerospace Standard 568 published by the Society of Automotive Engineers. These sizes are designated by dash numbers as shown on the 568 DASH Chart. For instance, an O-ring with an inside diameter (I.D.) of .362 .005” and a cross section (W) of .103 .003 is designated as: “AS568-110.”