A pipeline for the transport of a pressurized flowable medium, consisting of a metal tube corrugated transversely to its longitudinal direction and of a hose which is arranged in the same and consists of plastic. The control part provides a second region, which is adjacent to the first region, in which an image is formed using a dark-color toner and a light-color toner. The circuit also includes an electrical source in electrical communication with at least one of the first fluid and second fluid for selectively developing an electrical potential between fluid in the first channel and fluid in the second channel.