O-Ring Standard
Custom O-Rings
Where a standard AS568, metric or ISO 3601 size does not fit the application, FITCO produces custom O-rings to drawing — including non-standard cross-sections, oversize/undersize diameters, custom durometer and bespoke compound formulation, with prototype and low-volume production available before committing to full tooling.
Reference
Key points
| Diameter range | Custom, per drawing |
| Cross-section range | Custom, per drawing |
| Tooling | Compression, transfer or injection molds |
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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