An air purging coater apparatus is disclosed for purging mixed components from the apparatus disposed in a pipeline at a pipeline site. The apparatus includes a remote-controlled apparatus for insertion within the pipeline at the pipeline site. The remote-controlled apparatus includes a drive for controllably moving the remote-controlled apparatus internally within the pipeline. A high-pressure mixing device defines a first and second inlet controllably connected to a pressurized and further pressurized source respectively of a first and second component. The high-pressure mixing device defines a high-pressure mixing chamber connected to the first and the second inlets for mixing together the first and second components. The high-pressure mixing device defines an outlet connected to the high-pressure mixing chamber for receiving a flow therethrough of the mixed components. A spin head defines an internal conical surface and a baffle so that the mixed components are applied to an inside surface of the pipeline. The high-pressure mixing device is controllably movable from an application disposition thereof to a purging disposition. In the purging disposition, the flow of the mixed components is terminated and a source of pressurized air flows into and through the first and second inlets and the high-pressure mixing chamber and the outlet for purging any residual mixed components from the high-pressure mixing device thereby avoiding any need for the use of a potentially hazardous solvent.