O-Rings
Additional Information
There are several different standards to choose from when it comes to O-ring dimensions. The most popular in the United States is the AS568 standard for O-ring sizes and tolerances. Maintained by the Society of Automotive Engineers, this standard allows the user to choose from five different cross-sections with inside diameters ranging from 1/32" to 26". Tube fitting boss seals are included in AS568 as 900 series O-ring sizes, and are intended for use in MS33649 (now superseded by SAE-AS5202) straight thread tube fitings. RT/Dygert also offers a wide array of metric sizes, in both standard and non-standard dimensions. As a subset of the metric sizes offered, we also stock many Japanese Industrial Standard (JIS B2401) sizes. If an O-ring with special size or fluid resistance is required, RT/Dygert can provide custom O-rings, specially made to your demanding requirements.
SIZES
| Dimensions in Inches | Nominal Size (Reference Only) | |||||||
| ID | AS568A | I.D. | ± | C/S | Vol (in3) | I.D. | O.D. | C/S |
| 1186 | 001 | 0.029 | .004 | .040 ± .003 | .0003 | 1/32 | 3/32 | 1/32 |
| 1187 | 002 | 0.042 | .004 | .050 ± .003 | .0006 | 3/64 | 9/64 | 3/64 |
| 1188 | 003 | 0.056 | .004 | .060 ± .003 | .0010 | 1/16 | 3/16 | 1/16 |
| 1189 | 004 | 0.07 | .005 | .070 ± .003 | .0017 | 5/64 | 13/64 | 1/16 |
| 1190 | 005 | 0.101 | .005 | .070 ± .003 | .0021 | 3/32 | 7/32 | 1/16 |
| 1191 | 006 | 0.114 | .005 | .070 ± .003 | .0022 | 1/8 | 1/4 | 1/16 |
| 1192 | 007 | 0.145 | .005 | .070 ± .003 | .0026 | 5/32 | 9/32 | 1/16 |
| 1193 | 008 | 0.176 | .005 | .070 ± .003 | .0030 | 3/16 | 5/16 | 1/16 |
| 1194 | 009 | 0.208 | .005 | .070 ± .003 | .0034 | 7/32 | 11/32 | 1/16 |
| 1195 | 010 | 0.239 | .005 | .070 ± .003 | .0037 | 1/4 | 3/8 | 1/16 |
| 1196 | 011 | 0.301 | .005 | .070 ± .003 | .0045 | 5/16 | 7/16 | 1/16 |
| 1197 | 012 | 0.364 | .005 | .070 ± .003 | .0052 | 3/8 | 1/2 | 1/16 |
| 1198 | 013 | 0.426 | .005 | .070 ± .003 | .0060 | 7/16 | 9/16 | 1/16 |
| 1199 | 014 | 0.489 | .005 | .070 ± .003 | .0068 | 1/2 | 5/8 | 1/16 |
| 1200 | 015 | 0.551 | .007 | .070 ± .003 | .0075 | 9/16 | 11/16 | 1/16 |
| 1201 | 016 | 0.614 | .009 | .070 ± .003 | .0083 | 5/8 | 3/4 | 1/16 |
| 1202 | 017 | 0.676 | .009 | .070 ± .003 | .0090 | 11/16 | 13/16 | 1/16 |
| 1203 | 018 | 0.739 | .009 | .070 ± .003 | .0098 | 3/4 | 7/8 | 1/16 |
| 1204 | 019 | 0.801 | .009 | .070 ± .003 | .0105 | 13/16 | 15/16 | 1/16 |
| 1205 | 020 | 0.864 | .009 | .070 ± .003 | .0113 | 7/8 | 1 | 1/16 |
| 1206 | 021 | 0.926 | .009 | .070 ± .003 | .0120 | 15/16 | 1-1/16 | 1/16 |
| 1207 | 022 | 0.989 | .010 | .070 ± .003 | .0128 | 1 | 1-1/8 | 1/16 |
| 1208 | 023 | 1.051 | .010 | .070 ± .003 | .0136 | 1-1/16 | 1-3/16 | 1/16 |
| 1209 | 024 | 1.114 | .010 | .070 ± .003 | .0143 | 1-1/8 | 1-1/4 | 1/16 |
| 1210 | 025 | 1.176 | .011 | .070 ± .003 | .0151 | 1-3/16 | 1-5/16 | 1/16 |
| 1211 | 026 | 1.239 | .011 | .070 ± .003 | .0158 | 1-1/4 | 1-3/8 | 1/16 |
| 1212 | 027 | 1.301 | .011 | .070 ± .003 | .0166 | 1-5/16 | 1-7/16 | 1/16 |
| 1213 | 028 | 1.364 | .013 | .070 ± .003 | .0173 | 1-3/8 | 1-1/2 | 1/16 |
| 1214 | 029 | 1.489 | .013 | .070 ± .003 | .0188 | 1-1/2 | 1-5/8 | 1/16 |
| 1215 | 030 | 1.614 | .013 | .070 ± .003 | .0204 | 1-5/8 | 1-3/4 | 1/16 |
| 1216 | 031 | 1.739 | .015 | .070 ± .003 | .0219 | 1-3/4 | 1-7/8 | 1/16 |
| 1217 | 032 | 1.864 | .015 | .070 ± .003 | .0234 | 1-7/8 | 2 | 1/16 |
| 1218 | 033 | 1.989 | .018 | .070 ± .003 | .0249 | 2 | 2-1/8 | 1/16 |
| 1219 | 034 | 2.114 | .018 | .070 ± .003 | .0264 | 2-1/8 | 2-1/4 | 1/16 |
| 1220 | 035 | 2.239 | .018 | .070 ± .003 | .0279 | 2-1/4 | 2-3/8 | 1/16 |
| 1221 | 036 | 2.364 | .018 | .070 ± .003 | .0294 | 2-3/8 | 2-1/2 | 1/16 |
| 1222 | 037 | 2.489 | .018 | .070 ± .003 | .0309 | 2-1/2 | 2-5/8 | 1/16 |
| 1223 | 038 | 2.614 | .020 | .070 ± .003 | .0324 | 2-5/8 | 2-3/4 | 1/16 |
| 1224 | 039 | 2.739 | .020 | .070 ± .003 | .0340 | 2-3/4 | 2-7/8 | 1/16 |
| 1225 | 040 | 2.864 | .020 | .070 ± .003 | .0355 | 2-7/8 | 3 | 1/16 |
| 1226 | 041 | 2.989 | .024 | .070 ± .003 | .0370 | 3 | 3-1/8 | 1/16 |
| 1227 | 042 | 3.239 | .024 | .070 ± .003 | .0400 | 3-1/4 | 3-3/8 | 1/16 |
| 1228 | 043 | 3.489 | .024 | .070 ± .003 | .0430 | 3-1/2 | 3-5/8 | 1/16 |
| 1229 | 044 | 3.739 | .027 | .070 ± .003 | .0460 | 3-3/4 | 3-7/8 | 1/16 |
| 1230 | 045 | 3.989 | .027 | .070 ± .003 | .0491 | 4 | 4-1/8 | 1/16 |
| 1231 | 046 | 4.239 | .030 | .070 ± .003 | .0521 | 4-1/4 | 4-3/8 | 1/16 |
| 1232 | 047 | 4.489 | .030 | .070 ± .003 | .0551 | 4-1/2 | 4-5/8 | 1/16 |
| 1233 | 048 | 4.739 | .030 | .070 ± .003 | .0581 | 4-3/4 | 4-7/8 | 1/16 |
| 1234 | 049 | 4.989 | .037 | .070 ± .003 | .0612 | 5 | 5-1/8 | 1/16 |
| 1235 | 050 | 5.239 | .037 | .070 ± .003 | .0643 | 5-1/4 | 5-3/8 | 1/16 |
MATERIALS
Nitrile Rubber
RT/Dygert Stock Material
Other Designations
Buna N; NBR; Paracril® (Uniroyal)
Composition
Medium density copolymer of butadiene and acrylonitrile
Temperature Range
-40 to 250 °F
Description
On a cost basis, nitrile, or NBR, rubber is the least expensive of the oil resistant elastomers. As a result, nitrile is one of the most widely used rubber materials due to its combination of low cost, resistance to many chemicals, and good physical properties. The acrylonitrile content of this highly polar elastomer provides excellent oil and gas permeation resistance which increases as the level of ACN increases. Unfortunately, an increase in the acrylonitrile content compromises low temperature flexibility, and increases compound hardness. Typical ACN content ranges from 18% to 50%. Nitrile should not be exposed to direct sunlight or moderate to high levels of atmospheric ozone, as rapid deterioration will result. However, NBR will accept many antidegradants, most notably PVC, which offer some degree of improvement of these properties. Nitriles are usually sulfur cured, but peroxide curing is also possible, resulting in improved compression set.
Information above applies to the generic material. Specific compounds may exhibit different properties.
Physical Properties*
| Excellent | Good | Fair | Poor | |
| Abrasion resistance | • | |||
| Compression Set | • | |||
| Elongation | • | |||
| Flame resistance | • | |||
| Gas permeability | • | |||
| Low temperature flexibility | • | |||
| Tear resistance | • | |||
| Tensile strength | • |
Chemical Resistance*
| Excellent | Good | Fair | Poor | |
| Brake fluid | • | |||
| Dilute acids | • | |||
| Dilute alkalis | • | |||
| Hydraulic fluids | • | |||
| Ketones | • | |||
| Ozone | • | |||
| Petroleum oils | • | |||
| Silicone Fluids | • | |||
| Steam | • | |||
| Strong acids | • | |||
| Transmission fluids | • | |||
| Water | • | |||
| Weather | • |
*Excellent, good, fair and poor are intended to serve as general guidelines only. Actual testing in the application environment is always recommended.
Information above applies to the generic material. Specific compounds may exhibit different properties.