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Everything about NBR seals: material properties, oil and fuel resistance, and typical areas of application in industry and engineering.
NBR seals are sealing elements made from nitrile rubber (NBR), a synthetic rubber. The material is frequently used because it offers high resistance to oils, greases and fuels. Typical areas of application are the automotive industry as well as mechanical and plant engineering.
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Properties of NBR seals
- High resistance to oils and greases: NBR offers very good resistance to mineral oils, greases and fuels and is suitable for oil-exposed applications.
- Temperature resistance: Service range typically from approx. -30 °C to +100 °C, suitable for many industrial environments.
- Good mechanical strength: High abrasion and tear resistance for applications with mechanical load.
- Chemical resistance: Resistant to many chemicals, in particular non-polar solvents.
Areas of application
- Automotive industry: Use in engine and fuel systems.
- Mechanical engineering: Use in hydraulic systems, pumps and compressors.
- Oil and gas industry: Sealing in pipelines and tanks.
Advantages of NBR seals
NBR seals impress with their high oil and fuel resistance as well as their good mechanical load capacity. This makes them suitable for demanding industrial applications with continuous media exposure.
Difference from other sealing materials
Compared with EPDM seals, NBR seals offer significantly better resistance to oils and fuels. Silicone seals are more temperature-resistant, while FKM (Viton) exhibits higher chemical resistance. Neoprene (CR) offers a balanced combination of oil and weather resistance.
Limits and disadvantages of NBR
NBR seals show lower resistance to weather, ozone and UV radiation and are therefore primarily suitable for indoor applications. At temperatures below -30 °C, elasticity decreases, and use above about +100 °C is likewise limited.
Further versions
In addition to seals, NBR is also available as sheet material, for example as NBR sheet for technical cut pieces and individual applications.
Detailed description of NBR seals
Material composition and variants
NBR (nitrile rubber, also acrylonitrile-butadiene rubber) is a synthetic elastomer produced by copolymerisation of acrylonitrile and 1,3-butadiene.
Depending on the compound, the acrylonitrile content is between about 18 % and 50 % and significantly influences the material properties. A higher acrylonitrile content improves resistance to oils and fuels but reduces flexibility at low temperatures.
A lower acrylonitrile content increases cold flexibility but goes hand in hand with lower oil and fuel resistance. The choice of the suitable compound therefore always depends on the specific application.
Specific material grades and trade names
NBR is offered under various trade names, including Perbunan® and Europrene®. Depending on the area of application, different grades and hardness levels are available:
- Semperit P534 (NBR 60 Shore): High oil and fuel resistance, suitable for hydraulic applications and the automotive industry.
- Semperit P559 (NBR 70 Shore): For aromatic and aliphatic oils, use in demanding mechanical engineering.
- Semperit P627 (NBR 60 Shore, FDA-certified): For applications in the food industry, resistant to animal and vegetable fats.
- Cooper Standard A-NT 68-00 (NBR super): Resistant to transformer oil according to Siemens standard SN 53145-1, use in power supply.
Mechanical and thermal properties
- Abrasion resistance: High resistance to mechanical wear and friction.
- Compression set: Low permanent deformation under continuous load, permanently reliable sealing effect.
- Temperature resistance: Typical service range from approx. -30 °C to +100 °C. Special compounds can be used up to +120 °C or down to -40 °C.
Specific areas of application
- Automotive industry: Seals in engines, transmissions and fuel systems.
- Mechanical engineering: Sealing in hydraulic and pneumatic applications, e.g. hydraulic cylinders.
- Oil and gas industry: Sealing of pipelines and tanks with oil or gas contact.
- Food industry: Use of FDA-compliant NBR grades in pumps and mixing systems.
- Power supply: Sealing in transformers and oil-filled systems.
Distinction from other sealing materials
Compared with EPDM, NBR offers significantly higher oil and fuel resistance, while EPDM is superior in weather, ozone and UV radiation.
FKM (Viton) is characterised by higher chemical and thermal resistance and is used in particularly demanding applications. Neoprene (CR) offers a balanced combination of oil and weather resistance but does not achieve the oil resistance of NBR.
Disadvantages and limits of NBR seals
- Limited resistance to ozone, UV radiation and weather.
- Limited resistance to polar solvents, ketones, esters as well as strong acids and bases.
- Limited temperature service range with loss of elasticity at high temperatures.
Processing and availability
NBR seals are available as roll and sheet goods and are processed into flat and flange gaskets. Self-adhesive versions serve as an assembly aid and facilitate installation.
After production, a quality control is carried out to ensure consistent material and dimensional accuracy. The seals are then properly packed and dispatched.
NBR seals offer a reliable solution for oil- and fuel-exposed applications. When selecting the material, the limits typical of the material should be taken into account and alternative elastomers should be considered for special requirements.
Frequently asked questions about NBR seals
What is an NBR seal?
An NBR seal consists of nitrile rubber (NBR). The material is particularly suitable for applications with contact to oils, fuels and petrochemical media.
Where are NBR seals used?
NBR seals are used primarily in the automotive industry, in mechanical engineering as well as in hydraulic and pneumatic systems.
What advantages do NBR seals offer?
NBR seals are characterised by high resistance to oils and fuels, good abrasion resistance as well as reliable mechanical load capacity.
How temperature-sensitive are NBR seals?
The typical service range is between about -30 °C and +100 °C. Special compounds can be used up to +120 °C.
What chemical resistance do NBR seals have?
NBR is resistant to oils, petrol and many petrochemical products. Resistance to ozone, UV radiation and some solvents is limited.
How is the size of an NBR seal determined?
The dimensions depend on the components to be joined and the respective requirements regarding pressure, temperature and medium.
How are NBR seals maintained?
NBR seals should be kept clean and protected from direct UV radiation, ozone and unsuitable chemicals. Regular visual inspections support a long service life.
How long do NBR seals last?
The service life depends on operating conditions such as temperature, pressure and media contact. With suitable design, service lives of several years are usual.
Can NBR seals be used in the food industry?
Special, certified NBR grades are available for food contact. Standard NBR is not intended for this.
How are NBR seals installed?
The seals are placed in the designated grooves or surfaces and fixed by bolting or compression of the components.
Are NBR seals UV-resistant?
NBR offers limited UV resistance and is primarily suitable for applications without permanent sunlight.
How do NBR seals differ from other sealing materials?
Compared with EPDM or silicone, NBR offers significantly higher oil and fuel resistance, while other materials have advantages in weather or temperature range.
How is the tightness of an NBR seal checked?
Tightness is checked by visual inspections, pressure tests or application-specific leak tests.
Can NBR seals be adapted?
NBR seals can be produced as a cut piece or special shape in order to meet application-specific requirements exactly.