Nitrile (NBR) O-Rings
The most cost-effective elastomer for oil and fuel resistance, offering excellent mechanical properties for general industrial applications.
Key Properties & Advantages
- Oil Resistance: Excellent resistance to petroleum-based oils and fuels
- Cost Effective: Lowest cost among oil-resistant elastomers
- Compression Set: Good recovery properties for static seals
- Temperature Range: -30°C to +100°C (-22°F to +212°F) standard grades
- Tensile Strength: Good mechanical properties for dynamic applications
- Versatility: Wide range of hardness options (40-90 Shore A)
NBR Grades & Formulations
Standard NBR
General purpose
Good oil/fuel resistance
Cost-effective solution
Carboxylated NBR (XNBR)
Improved tensile strength
Better abrasion resistance
Enhanced tear resistance
Hydrogenated NBR (HNBR)
Higher temperature range
Improved chemical resistance
Longer service life
Mechanical Properties
| Property | Standard NBR | XNBR | Test Method |
|---|---|---|---|
| Hardness (Shore A) | 40-90 | 50-90 | ASTM D2240 |
| Tensile Strength (MPa) | 10-25 | 15-30 | ASTM D412 |
| Elongation at Break (%) | 200-600 | 200-500 | ASTM D412 |
| Compression Set (% @ 100°C) | 20-40 | 15-35 | ASTM D395 |
| Tear Resistance (kN/m) | 20-50 | 30-70 | ASTM D624 |
Limitations & Considerations
- Weather/Ozone: Poor resistance unless specially compounded
- Polar Solvents: Not recommended for ketones, esters, or strong acids
- Temperature: Becomes brittle at low temps, degrades above 100°C
- Steam/Water: Swells in hot water/steam applications
- Dynamic Seals: Limited performance in high-speed dynamic applications
Common Applications
- Automotive: Fuel systems, oil seals, gaskets
- Hydraulics: Piston seals, rod seals, hydraulic hoses
- Industrial: Oil/gas equipment, pumps, valves
- Agriculture: Farm equipment, irrigation systems
- Appliances: Washing machines, dishwashers
- General Machinery: Shaft seals, bearing seals
Frequently Asked Questions
HNBR (Hydrogenated Nitrile) has superior temperature resistance (-40°C to 150°C), better chemical resistance, and longer service life than standard NBR, but at 2-3x the cost. HNBR is recommended for demanding applications.
Standard NBR has limited compatibility with biodiesel (especially blends above B20). For biodiesel applications, we recommend HNBR or specially formulated NBR compounds with improved biodiesel resistance.
- Density: ~1.0 g/cm³ (typically floats in water)
- Burn Test: Burns with yellow flame and sooty smoke
- Oil Swell: Will swell in mineral oil but maintain integrity
- Hardness: Typical Shore A range of 50-90