Piston actuated rotary union

A rotary union, comprising:

• a housing having a bore in fluid communication with a media channel opening and a piston bore having an open end disposed at a radially offset distance with respect to the bore, the piston bore being fluidly isolated from the media channel opening and the bore, and is fluidly connected to an actuation port;
• a non-rotating seal carrier slidably disposed within the bore in the housing and having a media channel in fluid communication with the bore;
• an actuation arm connected to the non-rotating seal carrier and extending radially outwardly therefrom with respect to the bore, the actuation arm at least partially overlapping the open end of the piston bore;
• a piston slidably disposed within the piston bore and being unattached from the housing and actuation arm such that the piston can freely move axially within the piston bore independently from the housing and the non-rotating seal carrier during operation to define a variable piston volume between the piston and the piston bore, the variable piston volume being fluidly connected to the actuation port, the piston being adapted to extend out from the open end of the bore when a fluid pressure provided via the actuation port is present in the variable piston volume, the piston having an axially-outward face that contacts the actuation arm and being configured to releasably abut the actuation arm and to urge the actuation arm, and thus the non-rotating seal carrier, to displace relative to the bore when the piston displaces relative to the piston bore;
• and
• a seal disposed around the non-rotating seal carrier and disposed to create a sliding seal between the non-rotating seal carrier and the bore;
• wherein the non-rotating seal carrier is arranged to extend relative to the housing when the fluid pressure is present in the piston bore.