Nitrile Butadiene Rubber (NBR / Buna-N) is FITCO's highest-volume compound, engineered for mineral oil, hydraulic fluid, fuel and grease compatibility across hydraulics, pneumatics, pumps and general industrial equipment. Acrylonitrile (ACN) content is tuned per application: higher ACN for stronger oil resistance, lower ACN for better cold-flexibility.
| Temperature range | -30°C to +100°C |
|---|---|
| Hardness range | 40–90 Shore A |
| Relative cost | $ |
| Resists | Petroleum oils, hydraulic fluid (HL/HM/HV), diesel, water, silicone grease |
| Avoid with | Ozone/weather exposure, brake fluid, ketones, strong acids |
| Standards | AS568 / ISO 3601 / BS 4518 |
NBR — Nitrile isn't a single formulation — the grade below matters as much as the base compound once your application gets specific.
Lower acrylonitrile content trades some oil resistance for significantly better low-temperature flexibility — specify where cold-start or outdoor cold exposure is the bigger risk than fluid swell.
FITCO's default NBR grade — the balance point between oil resistance and cold flexibility that covers the large majority of hydraulic and pneumatic sealing requests.
Higher acrylonitrile content maximizes resistance to swelling in petroleum oils and fuels, at the cost of reduced flexibility in cold conditions — specify for continuous high-oil-content immersion.
Nitrile is supplied at 70 or 90 Shore A as standard — 70 for general static/dynamic sealing, 90 where higher extrusion resistance is needed at higher system pressure.
Not sure which sub-grade fits your application? Send us your fluid, temperature and pressure and our engineers will confirm — send an enquiry →
Physical property data — hardness, tensile strength, elongation, compression set and temperature resistance — tested to ASTM/ISO standards for each hardness grade FITCO stocks.
Full physical property data sheet — hardness, tensile strength, elongation at break, compression set and temperature resistance.
Download Datasheet →Full physical property data sheet — hardness, tensile strength, elongation at break, compression set and temperature resistance.
Download Datasheet →High-temperature, chemical-resistant sealing for oil & gas and process industries.
-15°C to +327°CNear-universal chemical resistance for the most demanding process seals.
-40°C to +150°CWater, steam and weather-resistant sealing — the wrong choice for mineral oil.
Compare NBR O-Rings against alternative compounds to confirm you have the right elastomer for your application.
NBR vs FKM Comparison →Select standard, cross-section and ID — get instant OD and material readout for NBR O-Rings.
Open Size Chart →Download the physical property datasheet for this compound — hardness, tensile strength, compression set and temperature resistance.
Download PDFs →Send us your fluid, temperature and pressure — our engineers will confirm the compound.
