Captured O-ring

Try http://www.allsealsinc.com/nationalorings.html . They have pages of specifications for all uses of o rings. Good luck.

A capture O-ring is the standard type. Sometimes captured refers to the o-ring being between wear rings; a ring with flat on one side and concave on other, sandwich o-ring between.

Groove dimensions can be had in the o-ring manufacturers catalogue or check using a Parker catalogue.

A captured o-ring refers to a groove that prevents the o-ring from falling out of the groove. I capture an o-ring by making the groove narrower than the tables recommend. I hold it in place by friction. Tha "accepted" way is a dovetail groove or a half dovetail. The full dovetail is much more difficult to machine especially if it cannot be machined on a lathe.

Parker has a very good manual describing the many types of o-rings and grooves.

I agree with this post. For true retention it applies to ID, OD or face seal applications. For face seal I know the detail is in SAE J1453. (don't ask me how I remember that??)

It really depends on the appication too. You could just apply it with an adhesive (that matches the application of course) or just use a grease to retain it during assembly.

Guy

I should have been specific... I agree with the "dovetail" reference.

I didn't say groove did I...my bad

I capture an o-ring by making the groove narrower than the tables recommend.

I have found this to be detrimental mostly, the groove dimension is specific to application and o-ring composition. A groove too small or tight can cause a fatigue of the o-ring due and unnecessary extrusion.

This depends on whether the o-ring is static or dynamic. A static o-ring does not fatigue by being compressed. In fact, for vacuum applications, a static o-ring can be compressed up to 50% to reduce helium permeation. I agree, however, that an over-compressed o-ring in a dynamic application would not only fail prematurely but would probably extrude and fail in shear on the first few strokes or rotations if friction didn't cause the parts to be too stiff to rotate or move.