Multi-passage (MP) rotary unions are used when more than one media are used simultaneously. An MP rotary union provides multiple seals between stationary connections and rotating equipment, such as a drum, index table, clutch, or spindle. The multiple independent passages permit the flow of the same or different media into or out of the rotating equipment. Power and fluid transfer media typically used with multi-passage rotary unions include hydraulic fluids, cutting fluids, air, or inert gas. Other media include steam, water, thermal oil, and coolant. When electrical power, signal, or data transfer is combined with fluid transfer, MP rotary unions include a through bore to accommodate a slip ring or are integrated directly with slip rings.
