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- What is an NBR seal?
NBR Seals and Gasket
NBR rubber (nitrile butadiene rubber) or Perbunan is a synthetic rubber, also known under the names acrylonitrile-butadiene rubber or simply "nitrile". NBR is a modern high-performance plastic used in various fields of sealing technology. It is notable that the acrylonitrile content ranges between 18 and 50 percent, which influences various properties.
The material NBR or nitrile rubber is an elastomer with excellent mechanical properties. NBR demonstrates high abrasion resistance and tensile strength and remains elastic over a wide temperature range (low compression set).
Its very good chemical resistance makes NBR an ideal material for seals, applicable for flat gaskets, O-rings, shaft sealing rings e.g., Simmering seals as well as hydraulic seals and pneumatic seals, seal kits and custom seals. In the following post, you will learn everything about NBR as a sealing material. Also, read our sealing knowledge and comprehensive overview of sealing materials.
NBR - Properties of NBR as a sealing material
NBR (acrylonitrile-butadiene rubber) is a modern elastomeric material with good resistance to a wide variety of chemicals. NBR is compatible with oils and fats such as fuels, diesel, kerosene, aliphatic hydrocarbons, natural gas, as well as diluted acids, alkalis, and alcohols. Thus, NBR demonstrates resistance to gasoline, making NBR seals generally gasoline-resistant.
The application range of NBR in terms of temperature is broad. Depending on the acrylonitrile content, NBR can be used from -30°C to +120°C (-22°F to +248°F).
The mechanical properties of NBR are also excellent. It has significant tensile strength and shows a minimal permanent set under elastic deformation.
Because of these properties, NBR seals are ideally suited for a variety of seal types such as hydraulic seals or pneumatic seals. Often-used alternatives to NBR material include EPDM and FKM. In comparison, FKM is less resistant to weathering, less heat-resistant, and not suitable for use with brake fluids.
EPDM, in contrast to NBR, has the drawback of having poorer resistance to fuels (gasoline, diesel, kerosene, mineral oils) and solvents. Also, EPDM is not suitable for use in the food industry.
NBR Seals and Gaskets - When should NBR not be used?
NBR is relatively sensitive to UV radiation and ozone, and therefore, it should not be exposed to these elements. If the requirement profile for mechanics, temperature, and chemical resistance still favors the use of NBR, one should expect an increased need for maintenance due to reduced operational lifespans.
NBR is incompatible with aromatic hydrocarbons such as benzene and toluene, as well as solvents like acetone (ketones), acetic acid esters, and chlorinated solvents including chloroform and dichloromethane.
Adjustment of the Properties of NBR Material
The first version provided is already clear, precise, and grammatically correct. However, to ensure the translation is as polished as possible, here is a slightly refined version:
The NBR material is available in various grades. The acrylonitrile content is adjusted to fine-tune its properties, enabling optimal application in specific areas. NBR is the material of choice for high operating temperatures!
A higher acrylonitrile content in the material extends its application range to higher temperatures, allowing the material to maintain its advantageous mechanical properties up to +120°C (+248°F). For lower temperatures, the acrylonitrile content can be decreased.
The acrylonitrile content also influences the chemical resistance. An increased amount of acrylonitrile enhances the material's resistance to oils, fats, fuels, and aliphatic hydrocarbons.
In addition, NBR is utilized with different material hardness levels, expressed in degrees Shore A. The two most common forms are 70° Shore A and 90° Shore A, with higher hardness providing greater pressure resistance.
What are the advantages of an NBR seal?
The mechanical properties of NBR are particularly advantageous. It is low-wear and therefore well suited for dynamic seals, e.g. as a hydraulic seal or pneumatic seal.
Chemical resistance is another great advantage of NBR. Due to the polar chemical groups in the polymer, it easily withstands non-polar substances such as fuels, oils and fats.
In addition, NBR is also available in a food-safe version and is therefore physiologically harmless. Please ensure that the respective seals are always marked with a respective certificate (e.g. FDA), as not every NBR is automatically food-safe. Due to its resistance to oils and diluted acids, it can be used in beverage production (water, dairy products and fruit juices).
It is also used in seals and machine parts in food production.
NBR has a high gas tightness, so that it can also be sealed against substances with a high volatility such as gasoline and also, for example, natural gas.
The advantages of NBR seals at a glance:
- high Shore hardness (high material hardness)
- high pressure resistance
- high temperature resistance up to +120°C (+248°F)
- outstanding mechanical properties
- strong resistance to chemical compounds such as: silicone or silicone oil, mineral oil, propane, butane, fuels such as diesel, petrol or kerosene, alcohol as well as acids and bases (alkalis)
Important: NBR does not have ozone resistance, materials such as EPDM seals are suitable here.
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NBR material - advantages over other elastomers
Nowadays, a variety of elastomers are available. Why should you choose NBR?
NBR, for example, outperforms CSM (chlorosulfonated polyethylene) and CR (chloroprene rubber) in terms of chemical resistance and resistance to fats and oils. If the elastomer comes into contact with fuels or oils during your application, you should consider NBR.
In addition, NBR is considered an inexpensive all-rounder among sealing materials, which is used as standard for most O-rings, for example.
Where are NBR seals used?
The properties of NBR make it a very versatile material that can be used in many areas.
Due to its resistance to oils and fuels, NBR is often the material of choice in the automotive industry. For example, NBR O-rings show resistance to gasoline and diesel. NBR flat gaskets are also used. In general, NBR is very popular in industry, e.g. in mechanical engineering as a hydraulic cylinder seal.
The partially physiological safety also makes it possible to use it in research and medicine. As a glove material, NBR is an excellent alternative to allergenic latex gloves. A wide variety of small parts are also manufactured from NBR in the chemical industry and pharmaceutical research, as they have good chemical resistance.
Standard NBR Seals and Custom-Made Seals
In the NBR Shop from Kofler – Dichtungen you can get rubber seals made of NBR according to your needs. We supply you with standard seals and gaskets such as flat gaskets, profile gaskets and O-rings.
In order to meet the most demanding applications, we also offer custom NBR industrial seals: we manufacture seals according to your wishes and specifications. Contact our seal experts today, they will be happy to hold a consultation with you and advise you on your options, so that you receive a custom-made NBR seal. You can have your seals made.
Send us the article number or the data sheet of your NBR seal, so we can keep production and or delivery times short!
