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 Tube fitting boss seals are included in AS568 as 900 series O-ring sizes, and are intended for use in MS33649 (now superseded by SAE-AS5202) straight thread tube fitings.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
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| AS568A | 901 | |
| Dash No. | ||
| US | Nominal | |
| I.D. | .185" ± .005" | |
| O.D. | .000" | |
| C/S | .056" ± .003" | |
| Volume | .002in3 | |
Gland Charts
MATERIALS
Butyl Rubber
Non-Stock Material
Other Designations
IIR
Composition
Medium density copolymer of isbutylene and a small amount of isoprene
Temperature Range
-40 to 275 °F
Description
Butyl rubber is a specialty rubber more frequently specified for its physical properties than chemical resistance. It has excellent shock absorption and vibration damping capabilities. Butyl's unusually low gas permeability makes it ideal for vacuum applications, while its high degree of unsaturation make it inherently resistant to atmospheric elements such as ozone and UV radiation. Additionally, butyl is thermally stable and has a relatively high coefficient of friction.
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 | |
| Ketones | • | |||
| Ozone | • | |||
| Petroleum oils and fuels | • | |||
| Silicone Fluids | • | |||
| 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.