Buna-N o-rings also referred to as NBR o-rings and Nitrile o-rings are the most widely used o-ring material in the word because of low cost, good mechanical performance with resistance to water, most basic oils, lubricants and some fuels, many pneumatic, hydraulic systems, and the default choice for basic applications. Buna-N o-rings are not recommended for exposure to sunlight, UV light, ozone and general outdoor weathering or hash chemicals, acids, keytones and many others.
Custom size Buna-N o-rings can typically be supplied without additional tooling fees within a few weeks. As the world’s largest o-ring inventory network, Marco Rubber’s direct purchasing power can deliver substantial savings on Buna-N o-rings. Order Buna-N o-rings online today!
|Recommended Use||Not Recommended For||Mechanical Properties|
| Silicone Greases / Oils
Petroleum Oils / Fuels
Ethylene Glycol Fluids
| Ketones (MEK)
Auto / Aircraft Brake Fluids
Sunlight, Ozone, Weathering
| Good Wear Resistance
Good Compression Set Resistance
Good Short-Term Resilience
Good Permeation Resistance
Popular Buna-N O-Rings Compounds:
Hundreds more specialty compounds available. Contact a Marco Sales Consultant or Engineer for more information.
|Marco Compound Number||Datasheet|| Hardness
|Color|| Low Temp.
| High Temp.
||70||Black||-31 (-35)||250 (121)||Lowest cost highest inventory general purpose commodity NBR compound. Compare to Parker N1470-70 and N0674-70 and Parco 4200-70 and 4900-70. Available in nearly any color and hardness.|
||90||Black||-31 (-35)||250 (121)||General purpose, higher pressure applications. Compare to Parker N0552-90 and N1490-90 and Parco 4200-90 and 4900-90.|
||70||Black||-31 (-35)||250 (121)||FDA compliant per 21 CFR 177.2600. Compare to Parker N0508-75 and N1069-70.|
||90||Black||-31 (-35)||250 (121)||FDA compliant, higher hardness.|
||50||Black||-31 (-35)||250 (121)||General purpose, lower hardness for lower closure force applications. FDA compliant and alternative colors available. Compare to Parker N0299-50.|
||80||Black||-31 (-35)||225 (107)||General purpose, higher hardness. Compare to Parker N0368-80.|
||70||Black||-31 (-35)||230 (110)||Internally lubricated with PTFE to reduce friction. Silicone oil and Moly (MOS2) internal lubricants available. Alternative hardness and colors also available.|
||70||Black||-35 (-37)||250 (121)||UL 157 listed for several approved uses.|
||70||Black||-31 (-35)||250 (121)||NSF 61 certified for drinking water applications.|
||95||Black||-31 (-35)||250 (121)||Very high hardness for extreme pressure applications.|
||70||Black||-65 (-54)||275 (135)||Improved lower and higher temperature resistance and improved oil resistance at higher temperature. Compare to Parker N0794-75 and M83461 and Parco 4367-70.|
||70||Black||-31 (-35)||250 (121)||Metal detectable for contamination detection sensors. FDA compliant per 21 CFR 177.2600. Formulated for food contact and life science applications. Additional colors available.|
||70||Black||-31 (-35)||250 (121)||NSF 51 certified for food contact.|
||70||Black||-65 (-54)||275 (135)||Mil Spec (Military specification) AMS-P-25732, MS28775-### per MIL-P-25732C-(1).|
||75||Black||-65 (-54)||275 (135)||Mil Spec (Military specification) AMS-P-83461, M83461/1-### per MIL-P-83461B#3. Improved low temperature resistance and hydraulic fluid resistance.|
||65||Black||-65 (-54)||250 (121)||Mil Spec (Military specification) MS29513-###, MS29512-##, AMS-P-5315B.|
||90||Black||-65 (-54)||275 (135)||Mil Spec (Military specification) MS28778, AMS-P-5510C.|
||65||Black||-70 (-57)||200 (94)||Mil Spec (Military specification) AMS7271, AS3578.|
Buna-N, Nitrile, NBR, Acrylonitrile Butadiene Rubber
Buna-N O-Rings Temperature Range
The temperature ranges presented above are approximations for dry air service only and should not be used to determine design specifications or end-use temperature limits. Actual temperature range of a compound in an end-use application is highly dependent on part type, hardware configuration, applied forces, chemical media, pressure and thermal cycling effects, and other factors. The most practical way of determining an end-use temperature range is testing in the actual application conditions. Consult a Marco Engineer for more details.
Buna-N O-Rings Typical Applications and Products:
The range of performance characteristics of Buna-N allows it to be utilized in a diverse set of applications. NBR is often used for gaskets and o-rings in pneumatic, hydraulic, and fuel systems. V-packings and backup rings made from high-hardness Nitrile compounds are common in high pressure environments in the Oil and Gas industry. The abrasion and wear resistance of NBR make it useful for dynamic oil seals for rotary and reciprocating shafts. NBR is relatively easy to process which keeps costs down for custom extrusions and complex molds. Hardness ranges from 40 Shore A to 90 Shore A. Hydrogenated versions of NBR (HNBR) have enhanced mechanical properties as well as greater thermal and chemical stability. Specific physical properties and chemical resistances vary by compound formulation.
NBR can be compounded for enhanced oil and fuel resistance, increased temperature flexibility, high hardness and extrusion resistance, low compression set, and a variety of other attributes. The physical properties of the compound largely depend on the Acrylonitrile content of the formulation. For example, high Acrylonitrile content causes increased oil and fuel resistance while adversely affecting low temperature flexibility and compression set resistance. It is important to consider the offsetting attributes when selecting an NBR formulation. Please contact a Marco Rubber engineer for assistance finding the best compound for your application.
Buna-N O-Rings Chemical Compatibility and Resistance:
- Petroleum greases, mineral oils, vegetable oils
- Aliphatic hydrocarbons
- Hydraulic fluids (HFA, HFB, HFC types)
- Limited resistance to dilute acids, alkalis, and solvents
Buna-N O-Rings Not Compatible With:
- Highly Aromatic fuels and hydrocarbons
- Weathering, sunlight and ozone
- Chlorinated hydrocarbons
- Polar solvents
- Glycol brake fluids
Buna-N O-Rings Compound and Product Options:
Not a complete list of offerings. Please contact a Marco Sales Consultant or Engineer to discuss additional options. See Popular Compounds list below for compound examples.
- Internal Lubrication with PTFE and others
- High strength
- Flame resistant
- ABS compatible
- WRAS, KTW and NSF Compliant
- FDA compliant
- Metal and X-ray detectable
- Gamma Radiation Resistance
- Tight and/or specific tolerances
- Specific AQL Inspection requirement
- Surface free of silicone oil
- PTFE coated in choice color
- Special tumbling for complete flash removal
- Talcum powder on surface to reduce sticking
- Specific packaging requirements
- Special bag and Label requirements
- Variety of colors available