Rotary union utilizing vacuum extraction

A rotary union comprising:

• a housing;
• a piston disposed within and extending through a proximal portion of the housing, wherein the piston comprises a first fluid passage therethrough and is configured to slide axially between a first position and a second position with respect to the housing;
• a shaft disposed within and extending through a distal portion of the housing, wherein the shaft comprises a second fluid passage therethrough and is configured to rotate with respect to the housing and the piston;
• a first port arranged in the proximal portion of the housing in fluid communication with a cavity formed between the housing and the piston, wherein the first port is configured to deliver a pressurized fluid into the cavity to actuate the piston from the first position to the second position;
• and wherein the first fluid passage of the piston is in fluid communication with the second fluid passage of the shaft and the piston is in contact with the shaft when the piston is in the second position;
• a chamber formed between the proximal and distal portions of the housing and surrounding an interface between the first fluid passage of the piston and the second fluid passage of the shaft, wherein outer and inner sidewalls of the chamber converge into a rounded base;
• and
• a second port arranged in the distal portion of the housing in fluid communication with the chamber, wherein the second port is configured to apply a vacuum to the chamber to evacuate fluid leaked into the chamber from the interface between the first fluid passage of the piston and the second fluid passage of the shaft, and wherein the second port extends through the distal portion of the housing tangentially to the outer side wall at the second port and tangentially to the rounded base at the second port.