A multi-pass rotary union (also called a multi-pass rotary joint) is a high-precision rotating-interface device designed to transmit two or more independent fluid (or gas) channels simultaneously between a fixed supply and a rotating machine component. Unlike single-pass unions that carry only one medium, multi-pass units enable multiple media — for example, coolant, hydraulic oil, air, steam, or vacuum — to flow through separate internal passages with full rotary motion and sealing integrity.
These unions are critical in systems where rotating drums, index tables, spindles, or swivel joints must receive multiple services (e.g., supply and return cooling lines, hydraulic actuators, pneumatic clamps) without external hose tangling or complex piping assemblies.
Compact integration of multiple fluid paths: A single unit can carry 2, 4, 8, or more channels, thereby reducing multiple individual unions and simplifying machine architecture.
Reduced risk of cross-contamination: Independent sealing design allows the rotary union to carry different fluids (such as hydraulic oil and coolant) without any mixing.
Improved system reliability & space-saving: Fewer leak points, fewer rotating fittings, less maintenance, and more robust machine uptime.
Flexibility in media and mounting: Many multi-pass units support various media types (liquid, gas), pressures, temperatures, and can be custom-configured.
When selecting a multi-pass rotary union, the following parameters are especially important:
Number of passages (channels): Depending on your needs, models range from 2 to 24 or more independent passages.
Media type(s): What fluids/gases will flow? Coolant, hydraulic oil, air, steam, vacuum, etc. Ensure the union materials and seals are compatible.
Pressure rating: Maximum operating pressure per passage. Example: some multi-pass unions support high pressures (310 bar or more).
Temperature range: Operating media temperature + ambient conditions; high-temperature or low-temperature environments require special materials.
Rotational speed (RPM): This is especially important when using the union in high-speed machinery, so engineers must ensure that the bearings and seals are rated accordingly.
Connection types & mounting: Threaded, flange mount, through-bore (for combined slip ring or electrical feed-through), etc.
Material & seal technology: Housing and shaft materials (steel, stainless steel, aluminum), seal types for media compatibility, bearing design for load and alignment.
Passage size & flow capacity: Each channel must support the required flow (volume) and minimal pressure drop, so size accordingly.
Custom vs standard: Many applications require tailored multi-pass unions (special passage counts, combined power/data slip rings, exotic media).
| Feature | Description |
|---|---|
| Passages | 2 to 12+ independent sealed channels |
| Media Types | Air, coolant, hydraulic fluids, inert gases |
| Max Pressure | Up to 4500 psig (310 bar) |
| Max Temperature | Up to 200°F (93°C) |
| Max Speed | Up to 250 rpm |
| Materials | Steel, stainless steel, aluminum, brass |
| Seal Technology | Carbon-fiber Teflon®, balanced mechanical seals |
| Mounting Options | Standard, flange, custom, with slip ring bore |
Numerous industrial sectors use multi-pass rotary unions. Typical use-cases include:
Rotary index tables and machining centres that need coolant, hydraulic, pneumatic, and electrical services.
Printing, packaging, and lamination machines where multiple fluid circuits (cooling, drying air, vacuum) feed a rotating drum.
Steel mills/roll mills: cooling, lubrication, hydraulic actuators, and feeding a rotating roll.
Marine/offshore swivel systems: multiple fluid lines (hydraulic, air, chemical) in a rotating loading arm.
Renewable energy systems (e.g., wind-turbine blade pitch control): multiple media through a rotating hub.
Automated factory equipment: multi-station rotary joints requiring several independent channels in one compact unit.
Available from 2 to 24 independent passages, enabling simultaneous transfer of multiple media — coolant, hydraulics, gas, vacuum, etc.
Low-friction design with precision bearings and robust seals, extending life and minimizing downtime
Each passage is individually sealed to prevent cross-contamination between media
Supports 360° continuous rotation without interruption, ideal for index tables, swivels, and rotating drums
Customisable mounting options, materials (steel, stainless), connection types (threaded, flange, through-bore), and ratings for pressure, temperature, and speed
Maintenance-friendly modular design: passages, seals, and bearings can be serviced or replaced, reducing the total cost of ownership
If you are designing or upgrading a machine that demands multiple fluid/gas services through a rotating interface, the Multi Passage Rotary Union category provides the solution you need to streamline design, improve reliability, and reduce maintenance. By selecting the correct number of passages, compatible materials, and performance ratings upfront, you position your system for long-term success.
Browse the models above, or contact our sales & engineering team for custom options tailored to high-channel count, high-speed, or high-pressure rotating applications.
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