O-Ring Standard
AS568 O-Rings
AS568 (Aerospace Size Standard 568) defines the inch-based dash-numbered O-ring sizes used as the de-facto global standard across hydraulic, pneumatic and general industrial equipment. FITCO manufactures the full AS568 dash-size range (-001 through -906+) in all core compounds.
Sample sizes
Representative sizes
| Dash / Size | ID (in) | CS (in) |
|---|---|---|
| -010 | 0.239 | 0.070 |
| -113 | 0.799 | 0.103 |
| -214 | 1.755 | 0.139 |
| -325 | 2.475 | 0.210 |
| -425 | 4.475 | 0.275 |
Available in
Compounds
Material
NBR (Nitrile / Buna-N)
NBR is the workhorse elastomer of the sealing industry — a copolymer of butadiene and acrylonitrile whose acry…
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FKM / FPM (Fluoroelastomer)
FKM (often referenced by the trade name Viton) is a fluorine-containing elastomer built for aggressive chemica…
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EPDM
EPDM's saturated backbone gives outstanding resistance to ozone ageing, UV and weathering along with strong pe…
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Silicone (VMQ)
Silicone offers the widest usable temperature range of any common elastomer and is available in FDA- and USP C…
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HNBR (Hydrogenated Nitrile)
Hydrogenating the NBR backbone removes most of the residual unsaturation, substantially improving heat, ozone …
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FFKM (Perfluoroelastomer)
FFKM replaces essentially all hydrogen with fluorine, approaching PTFE-level chemical inertness while retainin…
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