NBR 70A and FKM/Viton materials. Inch sizes per AS568 standard. Mixed sizes accepted in one order.
AS568 is the Aerospace Standard published by SAE International that defines the dimensions of O-rings in inch units. It is the most widely used O-ring size standard in North America and is recognized internationally.
Each AS568 number (also called a "dash number") specifies the inside diameter (ID) and cross-section diameter (CS) of the O-ring. For example, AS568-214 has an ID of 0.739" (18.77 mm) and a CS of 0.103" (2.62 mm).
The standard covers sizes from -003 (very small) to -475 (large), organized into groups by cross-section size. We supply the full range in NBR 70A and FKM/Viton materials.
| AS568 No. | ID (inch) | ID (mm) | CS (inch) | CS (mm) | NBR 70A | FKM / Viton | Hardness |
|---|---|---|---|---|---|---|---|
| AS568-003 | 0.040" | 1.02 | 0.040" | 1.02 | NBR | FKM | 70A ±5 |
| AS568-004 | 0.070" | 1.78 | 0.040" | 1.02 | NBR | FKM | 70A ±5 |
| AS568-005 | 0.101" | 2.57 | 0.040" | 1.02 | NBR | FKM | 70A ±5 |
| AS568-006 | 0.132" | 3.35 | 0.040" | 1.02 | NBR | FKM | 70A ±5 |
| AS568-007 | 0.164" | 4.17 | 0.040" | 1.02 | NBR | FKM | 70A ±5 |
| AS568-008 | 0.176" | 4.47 | 0.053" | 1.35 | NBR | FKM | 70A ±5 |
| AS568-009 | 0.208" | 5.28 | 0.053" | 1.35 | NBR | FKM | 70A ±5 |
| AS568-010 | 0.239" | 6.07 | 0.053" | 1.35 | NBR | FKM | 70A ±5 |
| AS568-111 | 0.301" | 7.65 | 0.070" | 1.78 | NBR | FKM | 70A ±5 |
| AS568-112 | 0.364" | 9.25 | 0.070" | 1.78 | NBR | FKM | 70A ±5 |
| AS568-113 | 0.426" | 10.82 | 0.070" | 1.78 | NBR | FKM | 70A ±5 |
| AS568-114 | 0.489" | 12.42 | 0.070" | 1.78 | NBR | FKM | 70A ±5 |
| AS568-115 | 0.551" | 13.99 | 0.070" | 1.78 | NBR | FKM | 70A ±5 |
| AS568-116 | 0.614" | 15.60 | 0.070" | 1.78 | NBR | FKM | 70A ±5 |
| AS568-117 | 0.676" | 17.17 | 0.070" | 1.78 | NBR | FKM | 70A ±5 |
| AS568-118 | 0.739" | 18.77 | 0.070" | 1.78 | NBR | FKM | 70A ±5 |
| AS568-119 | 0.801" | 20.35 | 0.070" | 1.78 | NBR | FKM | 70A ±5 |
| AS568-214 | 0.739" | 18.77 | 0.103" | 2.62 | NBR | FKM | 70A ±5 |
| AS568-215 | 0.801" | 20.35 | 0.103" | 2.62 | NBR | FKM | 70A ±5 |
| AS568-216 | 0.864" | 21.95 | 0.103" | 2.62 | NBR | FKM | 70A ±5 |
| AS568-217 | 0.926" | 23.52 | 0.103" | 2.62 | NBR | FKM | 70A ±5 |
| AS568-218 | 0.989" | 25.12 | 0.103" | 2.62 | NBR | FKM | 70A ±5 |
| AS568-219 | 1.051" | 26.70 | 0.103" | 2.62 | NBR | FKM | 70A ±5 |
| AS568-325 | 1.739" | 44.17 | 0.139" | 3.53 | NBR | FKM | 70A ±5 |
| AS568-326 | 1.864" | 47.35 | 0.139" | 3.53 | NBR | FKM | 70A ±5 |
| AS568-327 | 1.989" | 50.52 | 0.139" | 3.53 | NBR | FKM | 70A ±5 |
| AS568-328 | 2.114" | 53.70 | 0.139" | 3.53 | NBR | FKM | 70A ±5 |
| AS568-329 | 2.239" | 56.87 | 0.139" | 3.53 | NBR | FKM | 70A ±5 |
| AS568-425 | 3.739" | 94.97 | 0.210" | 5.33 | NBR | FKM | 70A ±5 |
| AS568-426 | 3.864" | 98.17 | 0.210" | 5.33 | NBR | FKM | 70A ±5 |
| AS568-427 | 3.989" | 101.32 | 0.210" | 5.33 | NBR | FKM | 70A ±5 |
| AS568-428 | 4.239" | 107.67 | 0.210" | 5.33 | NBR | FKM | 70A ±5 |
| AS568-429 | 4.489" | 114.02 | 0.210" | 5.33 | NBR | FKM | 70A ±5 |
* This table shows representative samples. Full range -003 to -475 available. Tolerances per AS568 standard. Other hardness grades (60A, 80A) available on request.
| Property | NBR 70A (Nitrile) | FKM / Viton |
|---|---|---|
| Temperature Range | −40°C to +120°C | −20°C to +200°C |
| Petroleum Oils | Excellent | Excellent |
| Hydraulic Fluids | Excellent | Good |
| Water / Steam | Good | Fair |
| Fuels (Gasoline) | Good | Excellent |
| Acids / Chemicals | Fair | Excellent |
| Ozone / Weathering | Poor | Excellent |
| Typical Color | Black | Brown or Black |
| Relative Cost | Standard | Higher (2–4×) |
| Best For | General industrial use, hydraulics, pneumatics | High-temp, chemical, fuel applications |
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