What is the difference between Rotary Joints and Rotary Unions?

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What is the difference between Rotary Joints and Rotary Unions?

In industrial equipment, several types of tools and parts are being used. Each one has some unique purpose and usage. You might have heard about rotary joints and rotary unions several times.

They are widely used in various industries, such as Textile, Paper, Food, Aluminum, Automotive, Cement, Leather, Plastics, Packaging, etc.

What are these parts?

Let’s understand this important industrial equipment in detail.

Rotary joints are also known as rotary unions or rotating unions.

It is a rotary sealing device. The purpose of this part is to connect rotating equipment to fixed piping for the transfer of water, coolant, hydraulic oil, steam, air, or any other media.

It is possible to design them with several types of passages so that multiple media types can be managed simultaneously.

In this case, a soft seal is used to prevent the fluids from “crossing over” into another passage. Typically, it is an O-ring.

In many industrial applications, soft seal multi-passage rotary unions are used widely. They are widely used in the oil and gas industries, food and beverage industries, medical devices, and even robotics.

You can find applications, where the rotary union is fitted along with slip rings. The purpose is to transmit electrical signals or hydraulic power.

In conventional rotary joints, a spring-loaded seal is used for keeping the gas medium or fluid from getting dispersed into the surroundings. Here, the use of the spring is to maintain the initial internal seating. The rotary joint is maintained pressure-sealed when it is in operation. To create the seal, a low-pressure or vacuum service is used on the spring force.

Conventional rotary unions are externally supported, or they are self-supported using an internal carbon guide. As far as the external support is concerned, it is given by mounting brackets or rods.

The fundamental purpose of rotary joints is to transfer medium from stationary supply lines to rotating or moving machine parts.

Not only that, but rotary unions can also be designed with several flow passages, and they can handle different media simultaneously. Whenever media is supposed to be transferred in rotating or swiveling machine parts, it comes out as the right solution.

Balanced seal rotary unions are popularly used with fluid service (e.g., water, coolant, etc.). However, they can also be used with steam and other gases.

The technology relies on optimizing the spring pressure to create a positive seal within the rotary union. The operating pressure of the media has hardly any effect on the sealing load. Balanced seals are typically flat face seals and in the rotary unions ball bearings are used for support. The seals are the main wearing components of a rotary joint and rotary union. When they are in operation, they experience internal loading forces from fluid pressure and friction from contacts between the faces of the sealing. When a seal fails, the media comes out. The efficiency of the entire heating or cooling process is adversely affected. Therefore, regular maintenance is important. It keeps the system in good health.

Also Read: Best Rotary Joints Manufacturers in India

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