O-Ring Sizes (AS568)
Standard AS568 (SAE ARP568) O-rings are grouped into five cross-section series by their dash number; the ID steps up within each series.
| Dash series | Cross-section (in) | Cross-section (mm) | Typical use |
|---|---|---|---|
| 0xx (004–050) | 0.070 | 1.78 | small — seals, glands |
| 1xx (102–178) | 0.103 | 2.62 | general purpose |
| 2xx (201–284) | 0.139 | 3.53 | larger bores / pistons |
| 3xx (309–395) | 0.210 | 5.33 | large diameter |
| 4xx (425–475) | 0.275 | 6.99 | very large diameter |
Look up an exact dash number's ID in the full AS568 table, then design the gland with the O-Ring Groove Designer.
A reference aid, not a substitute for engineering judgment. Verify against the governing standard.