O-Ring Gland Design with High Tolerance Conditions

In any type of application, there are consistent requirements to target when designing an adequate O-ring seal. Compression of the O-ring, gland fill of the O-ring within the gland, and stretch around the piston are critical considerations. A more detailed description of these requirements follows:

Squeeze: The amount that the “free state” cross-sectional diameter of the O-ring is compressed in the gland. The recommended range depends on the type of application and the cross-sectional width of the O-ring. The minimum amount of deflection for all O-ring seals is 0.007 inches, regardless of the cross-sectional thickness.

Gland fill: The percentage of the gland volume that is filled by the compressed O-ring. Between 70% and 95% gland fill is considered ideal. Excessive gland fill can cause sealing problems as well as contribute to early onset of permanent O-ring deformation.

Inner diameter (ID) stretch: For face seals, no ID stretch is required. For piston and bore type assemblies, ID stretch in the range of 0-5 % is recommended.

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