Rotary Union and Its Working Efficiency


Rotary union, or a rotary joint, as it’s sometimes called, enables the transfer of certain media, gases, water, and oils, from the stationary source to the rotating source. An important feature is that it provides a seal between the stationary and supply passage and a rotating part allowing the flow to be constant and preventing leakages. A stationary passage can be some sort of a pipe or a tube, while a rotating part is usually a certain kind of cylinder, drum, or a spindle.

The input valve is secured to the stationary media source which is connected with a rotating machine.

A rotary union is a part that enables rotation of the linked parts and provides a seal. It is typically associated with heat transfer media and fluid power media. Those include steam, oil, coolants, or water. Rotary union can also be called a swivel union or a swivel joint. They can integrate many independent flow channels for the transfer of different types of media at the same time. There are rotary union manufacturers that have a few decades of experience in making rotary unions for camera systems, medical equipment, and robotics.


Their design and application vary greatly, so it’s good to be able to count on the manufacturer to be able to deliver the best product for whatever you need.

Its potential industrial applications are numerous. When getting a rotary union, it’s important to consider its capacity. Also, the sizes and shapes differ a lot and the choice should be made depending on the device that it’s going to be used on.

Rotary unions tend to get damaged or to simply become a bit worn out. Many factors such as speed, pressure, temperature, volume, and flow velocity, determine how long the rotary union can keep doing its job. Normal rotational speed range from 0 to 1000 RPM (rotations per minute), while some can go as fast as 10,000 rotations per minute. Pressure from 0 to 20,000 PSI is considered normal, but some can withstand the pressure of over 40,000 PSI. When it comes to the temperature, anywhere between -150oF to +400oF can be considered normal.


When its efficiency is considered, it’s important to mention that the opening of the spring is always properly sealed. Also, new designs and improvements allow for the pressure to be detected and optimized more rapidly. Usually, rotary unions are made of black carbon steel or stainless steel helping it work properly for a long period of time. They are designed to be able to withstand different pressures, temperatures, and mediums.

As soon as the rotary union is installed, you can keep track of how it functions and see if it is positioned correctly. If it tumbles, vibrates, and makes noise, it means that it isn’t centered properly. All of the problems can be detected immediately and fixed which will help the rotary union to work longer. The proper positioning of the drain hose is also quite important. It should always slope downwards instead of upwards.