NBR (Nitrile) (acrylonitrile-butadiene rubber, typically 70 Shore A) is the default elastomer for oil and hydraulic sealing. When metric o-rings (iso 3601) are specified in this grade, the dimensions remain per ISO 3601-1 (fluid power — O-rings, inside diameters and cross-sections); the material determines corrosion behavior (good resistance to mineral oil, grease and hydraulic fluid; poor in ozone and weathering) and the service temperature range (approx. -30 °C to +100 °C). Both are covered below with the size table.
Why Choose NBR (Nitrile) for Metric O-Rings (ISO 3601)
The default elastomer for oil and hydraulic sealing. For metric o-rings (iso 3601), this matters when good resistance to mineral oil, grease and hydraulic fluid; poor in ozone and weathering is the primary requirement.
Mechanical & Physical Properties
| Grade designation | acrylonitrile-butadiene rubber, typically 70 Shore A |
|---|---|
| Magnetic response | Non-magnetic |
| Service temperature | approx. -30 °C to +100 °C |
| Corrosion characteristic | Good resistance to mineral oil, grease and hydraulic fluid; poor in ozone and weathering |
Galvanic & Galling Considerations
Galvanic and galling behavior do not apply to metric o-rings (iso 3601) in NBR (Nitrile) — the relevant compatibility questions are chemical: confirm the elastomer against the fluid, the temperature and any cleaning agents in service, and check the gland or groove dimensions give the intended compression on the section.
Comparable Grades
For metric o-rings (iso 3601), consider FKM where temperature or chemical exposure is higher, or EPDM where the medium is water, steam or brake fluid rather than oil. Elastomer selection is decided by the medium, the temperature range and whether the seal is static or dynamic — not by strength.
Sizes of Metric O-Rings (ISO 3601) Available in NBR (Nitrile)
| Cross-section (mm) | Typical inside-diameter range (mm) | Common compounds | Notes |
|---|---|---|---|
| 1.0 | 1.0 – 20 | NBR, FKM, EPDM, silicone | miniature and pneumatic |
| 1.5 | 2.0 – 40 | NBR, FKM, EPDM, silicone | small pneumatic and instrument |
| 1.78 | 1.78 – 50 | NBR, FKM, EPDM | nearest metric equivalent to the 1/16 in section |
| 2.0 | 3.0 – 100 | NBR, FKM, EPDM, silicone | general hydraulic and pneumatic |
| 2.5 | 5.0 – 150 | NBR, FKM, EPDM | general hydraulic |
| 3.0 | 6.0 – 200 | NBR, FKM, EPDM | general hydraulic |
| 3.5 | 10 – 250 | NBR, FKM | hydraulic |
| 4.0 | 12 – 300 | NBR, FKM | hydraulic and larger flanges |
| 5.0 | 20 – 400 | NBR, FKM | large flanges and covers |
| 5.33 | 20 – 400 | NBR, FKM | nearest metric equivalent to the 3/16 in section |
| 6.0 | 25 – 500 | NBR, FKM | large covers and housings |
Dimensions are independent of the material: every size above is available in NBR (Nitrile).
Custom manufacturing · Made to drawing
Need this seal in a grade that is not listed?
Nbr is one of the grades the catalog describes. Inside diameter, cross-section and compound are the three that matter, and the compound is chosen against the fluid and the temperature rather than the dimensions.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
