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AS568-238 O-Ring Size
200 series · 1/8" cross section · General purpose, cylinders
Inside diameter × cross section
88.49 × 3.53 mm
3.484″ × 0.139″ ·
outside diameter 95.55 mm (3.762″)
Dimensions
| Dimension | Inches | Millimetres |
|---|---|---|
| Inside diameter (ID) | 3.484″ | 88.49 mm |
| Cross section (CS) | 0.139″ | 3.53 mm |
| Outside diameter (OD) | 3.762″ | 95.55 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 88.49 mm, because compression set is permanent. If your measurement came in a little under this and the cross section roughly matches, -238 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) |
|---|---|---|---|
| -237 | 85.32 | 3.359″ | 92.38 |
| -239 | 91.67 | 3.609″ | 98.73 |
| -236 | 82.14 | 3.234″ | 89.2 |
| -240 | 94.84 | 3.734″ | 101.9 |