What is a rotary union? Types of rotary union & Components

What is a rotary union? Types of rotary union & Components

Rotary unions are rotating couplings that transfer fluids like steam, water, air, or oil from stationary sources to rotating equipment without leaking. The joint can also be called a rotary joint. Although all rotary unions perform the same functions, they differ based on their application. 

Bearings, seals, retaining rings, and O rings are all part of rotary unions, but their design and construction vary depending on their application. 

Various types of rotary unions based on passage and application

According to the flow of the passage 

Rotating unions can have a single passage or multiple passages. 

One-way heat transfer media are used in rotary unions with one passage. At one end of the union, the medium enters and exits to the other end, making it one passage. Multi-passage rotary unions have multiple passages in the same direction or different directions. 

According to application 

Rotary joint for hot applications with an outer body made of temperature-resistant steel, tungsten carbide seals, and graphite bushings that can withstand high fluid temperatures.

It is possible to retain high pressure when rotating at high speed with a high speed rotary joint. Stainless steel, carbon steel, and aluminum are used in high speed rotary unions, which are commonly used in extruders, laminators, hydraulic systems, and rubber mills. 

Components of rotary joint/joint

In rotary unions, the housing is the casing that contains all the components. The housing contains seals, O-rings, bearings, springs, shafts, and springs. Connected to the housing are pipes or hoses. 

Through the rotary union manufacturers, fluids are transferred from the shaft to the rotating cylinder or drum. The shaft is equipped with bearings and seals. 

The bearing is the most important part of a rotary union. Different circumstances and environments require different bearings. Housings rotate using roller bearings, non-roller bearings, and tapered bearings. 

During operation, the seal is one of the most important components of the rotary union. As a result of the seal opposing the fluid pressure, friction is generated between the stationary part and the rotating nipple. 

This spring forces the seal to contact the rotating shaft and prevents internal leaks, while also making sure that the seal is balanced with the surface on which it contacts. This feature is not available in all rotary unions. 

Applications of rotary union

Most rotary unions are used in automobiles and industrial machinery, where moving components require constant lubrication to operate smoothly. The chemical industry, the food industry, the cement industry, the textile industry, the packaging industry, and the pharmaceutical industry also use it.


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