Also referred to as a rotary joint, media joint, rotary coupling, fluid swivel, swivel joint or fluid rotary union (FRU).
Rotary unions are engineered for each unique application taking into consideration media types, number of flow paths, temperatures, pressures, speeds, loads, and environments.
A rotary union functions by connecting a stationary input (supply) to a rotating part, allowing a moving connection to be preserved and permitting the flow of media (liquids, solids and gases).
Rotary unions are utilized in a wide range of industries, from compact rotary unions for semiconductor applications, to large and rugged-duty rotary unions for energy, defense and industrial applications.
- Retaining Ring
Fluid Sealing & Transfer
Rotary unions (swivel joints) may integrate multiple independent flow channels (passages) for the sealing and transfer of different types of fluid media simultaneously. Common media types include:
- Food Products
Normal rotational speeds range from 0 to 1,000 RPM, with some high-speed rotary union applications requiring 10,000+ RPM.
Normal pressures range from 0 to 20,000 PSI [1,380 BAR], with some rotary union applications pushing the range of 40,000+ PSI [2,760 BAR].
Normal environmental and media temperatures for rotary union applications range from -150° F to +400° F. [-100° C to 200° C].
Application Example Hydraulic ExcavatorWatch Video
On an excavator, rotary unions allow hydraulic fluid to be transferred between the cab and track base while continuously rotating 360 degrees. The fluid supplies the track drive system allowing the excavator to move.
Application Example Wind TurbineWatch Video
On a wind turbine, rotary unions supply hydraulic fluid to power the turbine's blade pitch control system used to maintain optimum blade angle to achieve efficient power output. Rotary unions integrate hydrodynamic seal technology to provide long-life, maintenance-free operation required for wind turbines in offshore environments.
Application Example Offshore Hose ReelWatch Video
On an offshore hose reel, rotary unions (integrated with electrical slip rings) transfer hydraulic fluid, data and power signals through the reel hose down to subsea equipment. In some applications, pressurized hydraulics, power and data supply remotely operated vehicles (ROVs), allowing the control of subsea tools.