The budget-friendly oil & fuel seal
Great mechanical strength at low cost; not for ozone/weather or harsh solvents.
| Feature | Details |
|---|---|
| Also called | Buna-N, NBR, acrylonitrile-butadiene |
| Typical service temp | –40°F to +250°F (short term up to ~300°F, by compound) |
| Hardness range | 40–90 Shore A (most common: 50/70/90) |
| Cure systems | Sulfur (better low-temp) / Peroxide (better heat/CS) |
| FDA/NSF | Available in select compounds/colors |
| Actual limits vary by compound and media—verify in your service conditions. | |
BEST FOR
Petroleum oils & fuels, mineral/vegetable oils, diesel, lubricants- Ethylene glycol (antifreeze), silicone oils/greases
- Water/steam to 212°F (100°C)
- Need abrasion/tear resistance and good compression set at a good price
Not For
✘ Ozone/UV/weather exposure (outdoors)
✘ Automotive brake fluids (glycol), phosphate-ester hydraulic fluids (e.g., Skydrol)
✘ Ketones (MEK, acetone), esters/ethers, chlorinated or aromatic hydrocarbons
✘ Strong acids; high-temperature steam
Popular NBR Options
General Purpose: 50, 70, 90 durometer (black)
Low-Temperature: specialty 70/90 duros for colder start-up
Peroxide-Cured (heat/CS focus): typically 90 duro
FDA/NSF Grades: white/blue/black options
Metal/X-Ray Detectable (blue/green) • High-Visibility Green
Inch (AS568) and metric sizes. Custom sizes and colors on request.
Engineering Notes
ACN content (18–50%) drives behavior: lower ACN = better low-temp; higher ACN = better fuel resistance. Standard ~34% ACN is a common balance.
Sulfur vs Peroxide cures: sulfur = better low-temp; peroxide = better heat & compression set (often at higher cost).