O-Rings
AS568 O-Rings — Full Imperial Standard Range
The AS568 standard (published by the Society of Automotive Engineers) defines O-Ring sizes by a dash number system running from -001 to -475 across five cross-section bands. Every dash number specifies an Inside Diameter (ID) and Cross-Section (CS) in imperial inches. FITCO manufactures the complete AS568 range in all major elastomer compounds — NBR, FKM, FFKM, EPDM, HNBR, Silicone, AFLAS and more.
| Series | CS | ID Range |
|---|---|---|
| -001 to -050 | 1.78 mm (0.070") | 1.42–50.39 mm |
| -102 to -178 | 2.62 mm (0.103") | 1.42–75.79 mm |
| -201 to -284 | 3.53 mm (0.139") | 6.02–202.08 mm |
| -309 to -395 | 5.33 mm (0.210") | 18.64–660.32 mm |
| -425 to -475 | 6.99 mm (0.275") | 101.27–658.88 mm |
AS568 is the dominant standard in the United States and widely used globally in oil & gas, aerospace and industrial equipment. If your drawing shows a dash number (e.g. -214, -312), it is AS568.
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