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ROTARY UNION ® transfers media (water, steam, air, oil, hydraulic fluid, etc) from a stationary source to rotating machinery, such as a drum or an indexing table. They are used in process industries such as; paper, printing, rubber and plastics, textile and chemical. Rotary Unions are also used on cranes, machine tools and many other applications. Duff-Norton Rotary Unions are used to provide heating or cooling media like steam, hot oil, water or coolant to control the surface temperature of a drum or roll, to transfer air or hydraulic fluid to moving components or to add fluids to mixers while in motion. Rotary unions, rotary joints and rotating joints ranging up to 750 psi and up to 5,000 RPM are available.
Installation Information
Recommended Hose Installation

Flexible hose must be used to connect each Rotary Union to its supply or drain piping. Use braided metal hose for all applications involving hot fluids, such as, hot water, hot oil or steam. Use two-ply rubber hose for cooling water, refrigerants, air and vacuum service.

Allow for an offset between the Rotary Union joint and the rigid pipe as shown in Exhibit C. It is important to allow a slight curve in the house to allow the hose to "float". This will prevent a side load from being placed on the Rotary Union. A side load will greatly reduce the life of the Rotary Union.
Rotary Union: Hose installation diagram and dimensions
Exhibit C
Example of the correct way to install flexible hose on a
Rotary Union.
A straight hose, when fully charged, becomes rigid as solid pip. This rigidity, plus the added weight of the fluid media and expansion due to temperature, can drastically shorten the service life of the Rotary Union.