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AS568-138 O-Ring Size
100 series · 3/32" cross section · Hydraulics, pumps, valves
Inside diameter × cross section
53.64 × 2.62 mm
2.112″ × 0.103″ ·
outside diameter 58.88 mm (2.318″)
Dimensions
| Dimension | Inches | Millimetres |
|---|---|---|
| Inside diameter (ID) | 2.112″ | 53.64 mm |
| Cross section (CS) | 0.103″ | 2.62 mm |
| Outside diameter (OD) | 2.318″ | 58.88 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 53.64 mm, because compression set is permanent. If your measurement came in a little under this and the cross section roughly matches, -138 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 100 series
These share the same 3/32" 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) |
|---|---|---|---|
| -137 | 52.07 | 2.05″ | 57.3 |
| -139 | 55.24 | 2.175″ | 60.48 |
| -136 | 50.47 | 1.987″ | 55.7 |
| -140 | 56.82 | 2.237″ | 62.05 |