When it comes to sealing solutions, O-rings are a staple in countless industries, providing a reliable barrier against the leakage of fluids and gases. Two popular materials for O-rings are Nitrile Butadiene Rubber (NBR) with a 90 durometer rating and silicone. As a supplier of NBR 90 O Ring, I often get asked about how these two types of O-rings compare. In this blog post, I'll delve into the characteristics, advantages, and disadvantages of NBR 90 O-rings and silicone O-rings to help you make an informed decision for your sealing needs.
Material Properties
NBR 90 O-Rings
Nitrile Butadiene Rubber, commonly known as NBR or Buna-N, is a synthetic rubber copolymer composed of acrylonitrile (ACN) and butadiene. The "90" in NBR 90 refers to the durometer, which is a measure of the rubber's hardness on the Shore A scale. A durometer of 90 indicates a relatively hard rubber, which offers excellent resistance to abrasion, extrusion, and deformation under high pressures.
NBR 90 O-rings have outstanding resistance to oils, fuels, and petroleum-based fluids. They can withstand a wide range of temperatures, typically from -40°C to 120°C (-40°F to 248°F), making them suitable for applications in automotive, aerospace, and industrial machinery. Additionally, NBR has good mechanical properties, such as high tensile strength and elongation at break, which contribute to its durability and sealing performance.
Silicone O-Rings
Silicone is a synthetic elastomer made up of silicon, oxygen, carbon, and hydrogen. It is known for its excellent flexibility, high temperature resistance, and biocompatibility. Silicone O-rings can operate in a much wider temperature range than NBR 90 O-rings, typically from -60°C to 230°C (-76°F to 446°F), making them ideal for applications in extreme temperature environments, such as food processing, medical devices, and aerospace.
Silicone has a low compression set, which means it can maintain its shape and sealing properties even after prolonged compression. It is also resistant to ozone, weathering, and UV radiation, making it suitable for outdoor applications. However, silicone O-rings have relatively poor resistance to oils, fuels, and solvents compared to NBR 90 O-rings.
Performance Comparison
Sealing Performance
Both NBR 90 O-rings and silicone O-rings can provide effective sealing solutions, but their performance may vary depending on the application. NBR 90 O-rings are well-suited for applications where high pressure and resistance to oils and fuels are required. Their high hardness allows them to withstand extrusion and deformation under pressure, ensuring a tight seal.
Silicone O-rings, on the other hand, are better suited for applications where flexibility and high temperature resistance are crucial. Their low compression set and excellent elasticity enable them to maintain a seal even in dynamic applications or at extreme temperatures. However, their poor resistance to oils and fuels may limit their use in applications where contact with these substances is likely.
Chemical Resistance
As mentioned earlier, NBR 90 O-rings have excellent resistance to oils, fuels, and petroleum-based fluids. They are also resistant to many common chemicals, such as acids, alkalis, and solvents. This makes them a popular choice for applications in the automotive, aerospace, and industrial sectors, where exposure to these substances is common.
Silicone O-rings, on the other hand, have limited chemical resistance. They are not recommended for use in applications where contact with oils, fuels, or solvents is likely. However, they are resistant to many other chemicals, such as water, steam, and some food-grade substances, making them suitable for applications in the food processing, medical, and pharmaceutical industries.
Temperature Resistance
NBR 90 O-rings can operate in a temperature range of -40°C to 120°C (-40°F to 248°F), which is suitable for most industrial applications. However, their performance may degrade at higher temperatures, and they may become brittle at lower temperatures.
Silicone O-rings, on the other hand, can operate in a much wider temperature range of -60°C to 230°C (-76°F to 446°F), making them ideal for applications in extreme temperature environments. They can maintain their flexibility and sealing properties even at very low or very high temperatures, which is a significant advantage in industries such as aerospace, automotive, and food processing.
Durability
NBR 90 O-rings are known for their durability and long service life. Their high hardness and excellent resistance to abrasion and extrusion make them suitable for applications where they are subjected to high pressures and mechanical stress. They can also withstand repeated compression and relaxation cycles without losing their sealing properties.
Silicone O-rings, on the other hand, have a relatively low tear strength and may be more prone to damage from sharp edges or rough surfaces. However, their low compression set and excellent flexibility allow them to maintain a seal even after prolonged use, which can contribute to their overall durability.
Applications
NBR 90 O-Rings
- Automotive Industry: NBR 90 O-rings are widely used in automotive engines, transmissions, and fuel systems. They provide a reliable seal against oil, fuel, and coolant leakage, ensuring the proper functioning of the vehicle.
- Aerospace Industry: In the aerospace industry, NBR 90 O-rings are used in hydraulic systems, fuel systems, and engine components. Their high pressure resistance and excellent sealing performance make them suitable for applications where safety and reliability are critical.
- Industrial Machinery: NBR 90 O-rings are also used in industrial machinery, such as pumps, valves, and compressors. They provide a seal against fluid and gas leakage, preventing contamination and ensuring the efficient operation of the equipment.
Silicone O-Rings
- Food Processing Industry: Silicone O-rings are commonly used in food processing equipment, such as mixers, conveyors, and packaging machines. Their high temperature resistance, biocompatibility, and resistance to food-grade substances make them suitable for applications where hygiene and safety are important.
- Medical Industry: In the medical industry, silicone O-rings are used in medical devices, such as syringes, catheters, and respirators. Their biocompatibility and flexibility make them ideal for applications where contact with the human body is required.
- Aerospace Industry: Silicone O-rings are also used in the aerospace industry, particularly in applications where high temperature resistance and flexibility are required. They are used in engines, fuel systems, and environmental control systems to provide a seal against fluid and gas leakage.
Conclusion
In conclusion, both NBR 90 O-rings and silicone O-rings have their own unique advantages and disadvantages. NBR 90 O-rings are well-suited for applications where high pressure, resistance to oils and fuels, and durability are required. They are commonly used in the automotive, aerospace, and industrial sectors. Silicone O-rings, on the other hand, are better suited for applications where flexibility, high temperature resistance, and biocompatibility are crucial. They are commonly used in the food processing, medical, and aerospace industries.
When choosing between NBR 90 O-rings and silicone O-rings, it is important to consider the specific requirements of your application, such as temperature, pressure, chemical compatibility, and sealing performance. If you are unsure which type of O-ring is best for your needs, please feel free to contact us. As a leading supplier of NBR 90 O Ring, we have the expertise and experience to help you select the right sealing solution for your application. We also offer a wide range of other O-ring materials, such as O Ring As568 and O Ring Fkm 75, to meet your specific requirements.
References
- "Rubber Seals and Gaskets Handbook" by John H. Bickford
- "Elastomers and Rubber Compounding Materials" by Bernard G. Ranby
- "Sealing Technology Handbook" by John H. Bickford