Rotary unions and hybrid joints
Senring Pneumatic and hydraulic rotary unions (electrical-pneumatic) hybrid joint
Rotary unions with 1 to 24 passages and M5 to G1/2" ports, sold on their own or combined with 2 to 120 electrical circuits, for air, vacuum, water, steam and oils.
Key specifications
| Circuits (max) | 120 |
|---|---|
| Passages max | 24 |
| Ports | M5, G1/8", G1/4", G3/8", G1/2" |
| Media | compressed air, vacuum, water, steam, hot oil, hydraulic oil |
| Signal current | signal circuits under 2 A |
Summarised in our own words from SENRING Electronics Co., Limited's published data; series maxima, individual models vary. Last checked 2026-10-30. Source 1
Notes on this data
Pressure, speed and temperature not published on the page.
Specify Motion is not affiliated with SENRING Electronics Co., Limited. Senring and Pneumatic and hydraulic rotary unions (electrical-pneumatic) are used only to identify the product. Comparisons use published figures; always confirm against the current datasheet.
Typical applications
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What a rotary unions and hybrid joint is
A rotary union, also called a rotary joint or swivel, transfers fluids such as compressed air, vacuum, hydraulic oil, water or coolant from a fixed supply into a rotating shaft or table. A rotating shaft runs inside a stationary housing, and each fluid passage is isolated by seals between grooves, so several media can pass through one unit. Many designs combine with an electrical slip ring into one assembly, providing both fluid and electrical paths through continuous rotation.
When engineers choose a rotary unions and hybrid joint
Choose a rotary union when pneumatic grippers, vacuum cups, hydraulic clamps or cooling circuits sit on a rotating part. The alternative of hoses limits rotation to a few turns. The trade-offs are seal friction, leakage and wear: seal choice sets pressure, speed and media compatibility, and dry running damages some seals. Mixing vacuum and pressure in one unit needs suitable seals. Combining the union with a slip ring saves space but makes the assembly larger and more application-specific.
How to specify the Senring Pneumatic and hydraulic rotary unions (electrical-pneumatic)
Send these with your enquiry and an engineer can confirm the right Pneumatic and hydraulic rotary unions (electrical-pneumatic) variant or an equivalent:
- Number of passages and the medium in each
- Pressure and vacuum levels (bar)
- Flow rate or port size (l/min, mm or BSP)
- Fluid temperature (°C) and compatibility
- Speed (rpm)
- Permitted leakage and drain or vent provision
- Electrical circuits if combined with a slip ring
Common mistakes to avoid
- Running a union designed for lubricated media on dry air or without flow
- Not providing a leak drain between media and the electrical section of a combined unit
- Applying side load from rigid pipework instead of using flexible hoses and a torque arm
- Ignoring pressure spikes from valve switching when choosing seals
Senring Pneumatic and hydraulic rotary unions (electrical-pneumatic): frequently asked questions
What is the Senring Pneumatic and hydraulic rotary unions (electrical-pneumatic)?
Rotary unions with 1 to 24 passages and M5 to G1/2" ports, sold on their own or combined with 2 to 120 electrical circuits, for air, vacuum, water, steam and oils. Published series figures include circuits 120. It is made by SENRING Electronics Co., Limited; Specify Motion can help source it or propose an equivalent.
Who makes the Senring Pneumatic and hydraulic rotary unions (electrical-pneumatic)?
The Senring Pneumatic and hydraulic rotary unions (electrical-pneumatic) is made by Senring (SENRING Electronics Co., Limited) and is listed here for engineers comparing options. Specify Motion is not affiliated with SENRING Electronics Co., Limited; brand names are used only to identify the product.
What is the circuits of the Senring Pneumatic and hydraulic rotary unions (electrical-pneumatic)?
The published series maximum circuits is 120. Individual models and sizes in the Pneumatic and hydraulic rotary unions (electrical-pneumatic) range vary, so check the exact variant against your duty cycle, mounting and environment, or ask our engineers to confirm the right size for you.
Is there an alternative to the Senring Pneumatic and hydraulic rotary unions (electrical-pneumatic)?
Yes. Our engineers can propose an equivalent built around your load, speed and environment. An engineer confirms the fit against your application before recommending anything.
Can one rotary union pass air, vacuum and water at the same time?
Yes, multi-passage rotary unions isolate each medium in its own groove with seals between them. Each passage must be specified with its medium, pressure and flow, because seals that suit air may not suit water or vacuum. Leakage paths between passages and a drain for any seepage should be agreed with the supplier.
How is a rotary union combined with a slip ring?
A common layout puts the rotary union on the axis and the electrical slip ring around or beside it in a single assembly, so both fluids and electrical circuits pass through one rotating connection. The design must keep fluid away from the electrical rings, often with a drain chamber. Specify both parts together so the supplier can manage sealing, length and bearing loads.
Further reading: How to select a rotary union · How to select a slip ring · Slip rings
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