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AS568-228 O-Ring Size
200 series · 1/8" cross section · General purpose, cylinders
Inside diameter × cross section
56.74 × 3.53 mm
2.234″ × 0.139″ ·
outside diameter 63.8 mm (2.512″)
Dimensions
| Dimension | Inches | Millimetres |
|---|---|---|
| Inside diameter (ID) | 2.234″ | 56.74 mm |
| Cross section (CS) | 0.139″ | 3.53 mm |
| Outside diameter (OD) | 2.512″ | 63.8 mm |
Outside diameter is not measured, it is derived: OD = ID + 2 × CS.
If your measured OD disagrees with this, trust the ID and cross section — measuring
across the outside of a flexible ring is the least reliable of the three.
If you measured a used one
A ring pulled out of service will measure smaller than 56.74 mm, because compression set is permanent. If your measurement came in a little under this and the cross section roughly matches, -228 is very likely still the correct part. Ordering the size your worn ring measures is how the same failure repeats. More on this →
Nearby sizes in the 200 series
These share the same 1/8" cross section, so if the thickness is right but the diameter is off, your ring is probably one of these.
| Dash | ID (mm) | ID (in) | OD (mm) |
|---|---|---|---|
| -227 | 53.57 | 2.109″ | 60.63 |
| -229 | 59.92 | 2.359″ | 66.98 |
| -226 | 50.39 | 1.984″ | 57.45 |
| -230 | 63.09 | 2.484″ | 70.15 |