AS568-228 O-Ring

Inside diameter 2.234″
Cross-section 0.139″
Outside diameter 2.512″
Metric (ID × CS) 56.74 × 3.53 mm

OD is derived: ID + 2 × CS = 2.234″ + 2 × 0.139″ = 2.512″.

Neighboring sizes (CS 0.139″ series)

Dash ID OD ID mm vs -228
-226 1.984″ 2.262″ 50.39 ID −0.250″
-227 2.109″ 2.387″ 53.57 ID −0.125″
-228 2.234″ 2.512″ 56.74
-229 2.359″ 2.637″ 59.92 ID +0.125″
-230 2.484″ 2.762″ 63.09 ID +0.250″
Data provenance. SAE AS568, Aerospace Size Standard for O-rings (SAE International). Nominal dimensions per AS568; size tolerances vary by dash number and are not yet cataloged. Groove/gland design depends on the application — consult a gland design reference. See all data sources.