O-Ring Standard
ISO 3601 O-Rings
ISO 3601-1 defines metric O-ring dimensions and tolerance classes (Class A/B) and ISO 3601-2 defines gland dimensions; ISO 3601-3/4 cover quality acceptance criteria and material test methods. FITCO supplies ISO 3601 Class A and B O-rings with matching inspection documentation.
Reference
Key points
| Class A | Tighter tolerance — precision/critical sealing |
| Class B | Standard commercial/industrial tolerance |
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…
View details →Material
FKM / FPM (Fluoroelastomer)
FKM (often referenced by the trade name Viton) is a fluorine-containing elastomer built for aggressive chemica…
View details →Material
EPDM
EPDM's saturated backbone gives outstanding resistance to ozone ageing, UV and weathering along with strong pe…
View details →Material
Silicone (VMQ)
Silicone offers the widest usable temperature range of any common elastomer and is available in FDA- and USP C…
View details →Material
HNBR (Hydrogenated Nitrile)
Hydrogenating the NBR backbone removes most of the residual unsaturation, substantially improving heat, ozone …
View details →Material
FFKM (Perfluoroelastomer)
FFKM replaces essentially all hydrogen with fluorine, approaching PTFE-level chemical inertness while retainin…
View details →