Rotary Oil Seals: Nitrile Vs. FKM

Rubber rotary oil seals are crucial components in various machinery and industrial applications to prevent the leakage of fluids and protect the moving parts from external contaminants. When it comes to selecting the right rotary oil seal for a specific application, two common materials often come into consideration: Nitrile and FKM. Each material offers distinct characteristics that make them suitable for different operating conditions and environments. In this article, we will compare Nitrile and FKM rotary oil seals in terms of their properties, performance, and applications, helping you make an informed decision when choosing the right seal for your machinery.

Nitrile Rotary Oil Seals

Nitrile rubber, also known as NBR (Nitrile Butadiene Rubber), is a synthetic rubber copolymer widely used in the manufacturing of rotary oil seals due to its excellent compatibility with oils, fuels, and greases. Nitrile seals offer good resistance to abrasion, tearing, and compression set, making them ideal for applications where petroleum-based fluids are present. The flexibility and resilience of Nitrile rubber allow for a tight seal, ensuring minimal fluid leakage and preventing the entry of contaminants into the system. Additionally, Nitrile seals exhibit low permeability to gases, further enhancing their sealing effectiveness in rotary applications.

Despite their many advantages, Nitrile rotary seals have limitations when exposed to extreme temperatures or harsh chemicals. High temperatures can cause Nitrile rubber to degrade, resulting in reduced sealing performance and premature failure. Additionally, Nitrile seals may not be suitable for applications involving exposure to ozone, weathering, or certain chemicals that can cause deterioration of the rubber material. Therefore, it is essential to consider the operating conditions and environment in which the rotary oil seal will be used before choosing Nitrile as the sealing material.

FKM Rotary Oil Seals

FKM (Fluoroelastomer) is a synthetic rubber material known for its exceptional resistance to high temperatures, fuels, oils, chemicals, and solvents. FKM rotary oil seals offer superior heat resistance, making them ideal for applications requiring continuous operation at elevated temperatures. The excellent chemical resistance of FKM seals allows them to withstand exposure to a wide range of fluids and gases, ensuring reliable sealing performance in demanding environments. The high tensile strength and elongation properties of FKM rubber contribute to its durability and longevity in rotary sealing applications.

One of the key advantages of FKM rotary oil seals is their ability to maintain flexibility and sealing integrity over a broad temperature range, from -20°C to 200°C or higher, depending on the specific FKM compound used. This temperature versatility makes FKM seals suitable for a wide range of industrial applications where Nitrile seals may not perform optimally. Additionally, FKM seals are resistant to ozone, UV radiation, and weathering, providing added protection against environmental factors that can degrade the sealing material over time.

Comparison of Properties

When comparing Nitrile and FKM rotary oil seals, several properties must be considered to determine the most suitable material for a specific application. The table below outlines the key properties of Nitrile and FKM seals for comparison:

| Property | Nitrile Rotary Seals | FKM Rotary Seals |

|--------------------------|----------------------------------------------|----------------------------------------------|

| Temperature Resistance | Limited operating temperature range | Wide operating temperature range |

| Chemical Resistance | Good resistance to oils and petroleum fuels | Excellent resistance to various chemicals |

| Compression Set | Moderate resistance to permanent deformation | Low compression set for consistent sealing |

| Flexibility | High flexibility for tight sealing | Excellent flexibility over a broad temp. range|

| Durability | Moderate durability in certain environments | High durability in harsh conditions |

Applications

The choice between Nitrile and FKM rotary oil seals depends on the specific requirements of the application and the operating conditions in which the seals will be used. Nitrile seals are commonly used in general-purpose machinery, automotive applications, and equipment where exposure to petroleum-based fluids is prevalent. Their cost-effectiveness and reliable sealing performance make them a popular choice for a wide range of industries. However, in applications requiring resistance to high temperatures, aggressive chemicals, or extreme environmental conditions, FKM seals are the preferred option due to their superior properties and performance capabilities.

FKM rotary oil seals find applications in industries such as aerospace, automotive, chemical processing, and food processing, where the sealing requirements are more stringent and demanding. The ability of FKM seals to withstand extreme temperatures, harsh chemicals, and challenging operating conditions makes them well-suited for critical applications where failure is not an option. The versatility and reliability of FKM rotary seals have made them a preferred choice for industries that prioritize performance, longevity, and efficiency in their machinery and equipment.

Conclusion

In conclusion, both Nitrile and FKM rotary oil seals offer unique properties and advantages that cater to specific applications and operating conditions. Nitrile seals provide good general-purpose sealing for applications with moderate temperature and chemical exposure, while FKM seals excel in high-temperature, chemically aggressive environments where superior performance is required. By understanding the differences between these two materials and considering the specific requirements of your application, you can select the most suitable rotary oil seal to ensure optimal sealing performance and equipment reliability. Whether you choose Nitrile or FKM, investing in high-quality rotary oil seals is essential for maintaining the efficiency and longevity of your machinery and equipment.