Rotary Unions: Key to Efficient Fluid Transmission in Diverse Industrial Applications

Rotary Unions, also known as rotary joints, are critical components that facilitate fluid transmission between rotating equipment and stationary pipelines. These versatile devices can handle a wide variety of fluid types, each with unique physical and chemical properties that impose specific design requirements. A deep understanding of these fluids and their corresponding design considerations is essential for the correct selection, efficient operation, and long-term stable use of rotary unions.

Common Types of Transportable Fluids

Water

Water is one of the most common fluids used in industrial applications. Rotary Unions are frequently employed in cooling systems, cleaning equipment, and other processes where water needs to be transferred. For instance, in mechanical processing equipment, water is used to cool high-speed rotating tools, and Rotary Unions ensure the seamless introduction of water into the rotating components.

Steam

Steam plays a vital role in industrial heating, drying, and sterilization processes due to its high heat energy content. In industries such as paper manufacturing and food processing, rotary unions are essential for transmitting steam. These rotary unions must be designed to withstand high temperatures and pressures, ensuring reliable performance in demanding environments.

Oil

Various types of lubricating oils and hydraulic oils are indispensable in the lubrication and power transmission systems of rotating equipment. Rotary unions are commonly used in machine tool worktables and industrial robot joints to transmit oil fluids, ensuring proper lubrication and smooth operation of the equipment.

Gas

Compressed air, nitrogen, and other gases are often transmitted through rotary unions. In automated production lines, rotary actuators driven by compressed air rely on rotary unions for air supply. In specialized processes like semiconductor manufacturing, inert gases such as nitrogen are delivered to rotating components via rotary unions, ensuring precise and contamination-free operations.

Special Considerations for Designing Rotary Unions for Different Fluids

Water

Sealing Design: Due to water's low viscosity, high-precision sealing structures such as mechanical seals are required in rotary unions to prevent leakage. Materials like silicon carbide are often used to enhance wear resistance and corrosion resistance.

Material Selection: Corrosion-resistant materials like 316L stainless steel are preferred for parts of the rotary union that come into contact with water, ensuring durability and stability in water environments.

Steam

High Temperature and Pressure Resistance: Rotary unions for steam must be constructed from high-temperature alloy steel and use sealing materials like graphite or polytetrafluoroethylene to withstand extreme conditions.

Thermal Expansion Compensation: Design features such as flexible connections or expansion joints are incorporated to accommodate thermal expansion and prevent seal failure.

Oil

Lubrication Performance: The internal flow channels of rotary unions must be optimized to ensure smooth oil transmission and effective lubrication.

Leak Prevention and Compatibility: Sealing materials must be compatible with the specific oil type to prevent degradation and leakage, ensuring long-term reliability.

Gas

Low Leakage Seals: Multi-stage sealing structures, combining labyrinth seals and rubber seals, are used to minimize gas leakage.

Pressure Adaptation: Rotary unions must be designed to handle varying gas pressures, with robust materials and structures to prevent rupture or failure.

Conclusion

Rotary unions are indispensable for transporting various types of fluids in industrial applications. Each fluid type presents unique challenges that require careful consideration in the design of rotary unions. By addressing aspects such as sealing, material selection, and structural design, rotary unions can efficiently and safely handle diverse fluids, meeting the needs of various industrial processes. Rotary unions ensure the seamless and reliable operation of rotating equipment, making them a cornerstone of modern industrial systems.