An o-ring may be easily damaged by improper handling and may fail for this reason alone. Prior to o-ring installation, make sure that all glandular surfaces are free of all debris. If necessary, clean these surfaces with an appropriate solvent that is compatible with the o-ring being installed.
Before installation, make sure to lightly coat the o-ring with a lubricant that is compatible with the o-ring being installed, as well as compatible with system chemicals.
In piston applications, avoid stretching the o-ring more than 100% during installation (stretch should not exceed 5% in the application). Also, be sure to stretch it uniformly. Cones, or mandrels, are often used to assist in these installations. Once the o-ring has been installed, make certain to remove any twists.
When the piston is pushed into the cylinder, push it straight in. Do not turn or twist pistons into cylinders as this may bunch or cut o-rings.
In installations where the o-ring must pass over threads or other sharp edges, cover these edges with tape or a plastic thimble prior to o-ring installation.
As necessary, o-rings may be folded into internal grooves, but excessive twisting should again be avoided.
In hydraulic systems, it is recommended that glandular surfaces be washed with hydraulic fluid, then cleaned with a lint-free cloth.
In all cases of o-ring installation, try to avoid excessive twisting, turning, rotating, or oscillating of glandular components relative to the o-ring. Also try to avoid o-ring contact with any sharp surfaces, including fingernails.
One general guideline to consider when designing a seal is to maintain a range of % squeeze on the o-ring (~10-40% for static and no more than 30% for dynamic).
No less than 75% of the seal cross-section should be contained within the groove to ensure the seal doesn't “roll” or extrude out of the groove. See the Operating Environment Factors section for more detail on determining the allowable clearance gap.
Finally, be sure to consider the void/volume relationship in worst case tolerance conditions. The maximum o-ring volume should not exceed 90% of the minimum gland void. The groove width may be increased to provide additional void.
- Table A: O-Ring Gland Design for Dynamic Seals
- Table A: O-Ring Gland Design for Static Seals
- Table B: Static Axial Seal Gland Dimensions
- Table C: Static Radial Seal Gland Dimensions
- Table D: Static Crush Seal Gland Dimensions (for Triangular Grooves)
- Table E: Table E Dovetail Gland Dimensions
- Table F: Dynamic Radial Seal Gland Dimensions
- Table G: Rotary O-Ring Seal Gland Dimensions Under 900 PSI