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What is a Rotary Union? Where can they be used?

Featured Product from Deublin Co.

What is a Rotary Union? Where can they be used?-Image

What is a Rotary Union?

Generally spoken a Rotary Union is a precision mechanical device used to transfer fluid from a stationary source, such as a supply pipe, into a rotating piece of machinery.

Rotary Unions are used in numerous manufacturing processes to cool, heat or transfer fluid (pneumatic or hydraulic) power.

Rotary Union applications include Air Clutches, Gear Boxes, Machine Tool Spindles, Textile Equipment, Rubber & Plastic Manufacturing Machinery, Steel Continuous Casting Machines, Paper Machine Calender stacks, Paper Machine Dryer Cans, etc.

Typical rotary unions feature deep groove ball bearings to support the rotating component against the stationary component, and balanced, precision-engineered mechanical seals to seal the media flow.

Mechanical seal face materials and secondary seals will vary depending upon the fluid properties & operating conditions of the application. Likewise, bearing type, design, material & construction will also vary with application.

Original rotary unions used the media pressure to maintain seal contact. Logic indicates that as pressure increases, so do the forces holding the seals together - more pressure = tighter, "better" sealing. This is why they were called "pressure joints".

However, more pressure on the rotating seal face also meant more friction, higher torque and more wear. The resulting service life was not satisfactory.

DEUBLIN was aware of the disadvantage and applied "Balanced Mechanical Seal Technology", a decisive improvement.

This simply means the load or pressure on the seal faces is kept to a minimum regardless of media pressure, resulting in a freer turning union and in longer seal life. Optimal balance ratio allows for a thin film of "lubricating" media between the seal faces. In order to attain sealing in a non-pressurised system, the floating seal contact is maintained by the spring pressure.

The core of a rotating union is the seal combination. Seal faces manufactured from tool steel, carbon graphite, bronze, ceramic, tungsten carbide or silicon carbide are micro-lapped to a surface finish of 0.025 RMS and an optical flatness of 2 light bands. To ensure the above specifications the near perfect flatness is tested under mono-chromatic light.

Here are just some of the industries that rely on DEUBLIN for their unique Rotary Union needs:

  • ALUMINUM
  • AUTOMOTIVE
  • CAN MAKING
  • CAR WASH EQUIPMENT
  • CHEMICAL/PETROCHEMICAL/REFINERY
  • CONSTRUCTION EQUIPMENT
  • DISTILLERIES/BREWERIES
  • FARM EQUIPMENT
  • FLOOR & WALL COVERINGS
  • FOOD PROCESSING MACHINERY
  • GLASS MANUFACTURING
  • INSULATION
  • LAUNDRY EQUIPMENT
  • LUMBER & WOODWORKING
  • MACHINE TOOL
  • MARINE
  • MINING
  • PAPER
    • CONVERTING PLANTS
    • CORRUGATING
    • PULP & PAPERBOARD
    • ROOFING
  • PETROLEUM
  • PLASTICS
  • PRINTING
    • BUSINESS FORMS
    • FLEXOGRAPHIC
    • WEB OFFSET
  • RUBBER
  • STEEL
  • TEXTILE
  • TIRES

TRUCKING

Rotating Unions are also known in the industry by the following terms:

  • Rotary Unions
  • Rotary Joints
  • Rotating Joints
  • Steam Joints
  • Steam Fits
  • Swivels
  • Couplings
  • Rotating Couplings
  • Hydraulic Couplings
  • Rotary Couplings
  • Rotary Swivels
  • Hydraulic Swivels
  • Pneumatic Couplings
  • Pneumatic Swivels

These advanced machining techniques and proprietary processes allow DEUBLIN to achieve the most precise tolerances in the industry, and ensure superior union performance and service life.