Abstract: A rotary union for dispensing of a single central supply of water-based can sealing compound to an orbiting can end lining station includes a rotating reservoir (1) inside a stationary housing (2) with a dip tube (3) carried by the housing extending down below the liquid level of the reservoir. A sensor (4) in the ceiling of the housing determines the liquid level for controlling the admission of the compound through the down tube in response to the level sensed. The seal (7), where the stationary and rotating parts interface, is below the reservoir and simply needs to support gas pressure but does not come into contact with the compound.