What Is A Rotary Union And How It Can Be Sealed Effectively?

What is a Rotary Union and how it can be sealed effectively?

A rotary joint is a connector used to transfer fluid media in rotating equipment. It allows fluid to be transferred from a stationary pipe or system to a rotating component, such as a rotating shaft while maintaining a seal to prevent leakage.

The following is an introduction to rotary joints and their effective sealing:

The components of the rotary joint include:

• Housing: The housing is the outer structure of the rotary joint and is used to fix and support the internal components.
• Rotating shaft: The rotating shaft is the part that connects the rotating joint to the rotating component (such as a rotor or drum). It allows rotational movement and transfer of fluid media.
• Sealing device: The sealing device is a key component of the rotary joint and is used to ensure the sealing performance of the fluid. It usually consists of sealing elements such as sealing rings, sealing gaskets, or sealing rings. Rotary joints are widely used in many different applications. Here are some common application areas:
• Rotating Machinery: Rotary joints are commonly used in rotating machinery such as rotating shafts, rotors, drums, wind turbines, etc. They are used to transfer liquid media (such as lubricating oil, coolant, hydraulic oil, etc.) or gaseous media (such as compressed air, gas, etc.).

Where are rotary joints used?

• Chemical Process: In chemical processes, rotary joints are used to transport chemicals, solvents, gases, and other fluid media. They provide sealing and fluid transfer functions in rotating equipment such as agitators, spin dryers, centrifuges, etc.

• Oil and Gas Industry: Rotary joints play an important role in the oil and gas industry. They are used in oil well drilling equipment, oil field production equipment, pump stations, rotating platforms, etc. to transfer liquid media, gases, and mixtures.
• Medical Equipment: Rotary joints play a key role in medical equipment. For example, they are used in rotating parts in medical imaging equipment (such as CT scanners, MRI machines) to transmit power, signals and cooling media.
• Textile industry: In the textile industry, rotary joints are used in equipment such as spinning machines, looms, and textile machinery to transfer textile liquids (such as dyes, auxiliaries, and detergents) and gases.
• Food and Beverage Industry: Rotary joints are used in the food and beverage industry to transport fluid media such as food ingredients, food additives, syrups, beverages and liquid condiments.

Material Selection in Rotary Seals
There are several factors to consider when selecting a material for a rotary seal. Material selection depends on a variety of factors, including operating conditions, sealing media, temperature, pressure and speed. Here are some materials commonly used for rotary seals:

• Nitrile Butadiene Rubber (NBR): Has good low-temperature flexibility and is cost-effective. However, it may not be suitable for applications involving high temperatures or exposure to chemicals.
• Fluoroelastomer (FKM): Can withstand exposure to a wide range of liquids and is often used in harsh applications that require resistance to corrosive chemicals and high temperatures.
• Polytetrafluoroethylene (PTFE): Often used in rotary seals in combination with other materials such as elastomers or metal springs to improve sealing performance.
• Polyurethane (PU): Can handle a variety of fluids, including hydraulic oil, and is commonly used in hydraulic systems.
• Silicone (VMQ): Suitable for sealing applications involving extreme temperature ranges, such as low or high-temperature environments. However, silicone may not be compatible with certain chemicals.

• Ethylene propylene diene monomer (EPDM): EPDM seals are known for their excellent resistance to weathering, ozone, and aging. They perform well in water and steam applications and can also handle some chemicals. However, they may not be suitable for applications involving oils and hydrocarbons.