The device has a liquid tank (1), a propelled liquid pump, and a dosing device comprising an extraction pipe and a cleaning device (21) for providing cleaning fluid, where the cleaning device has cleaning nozzles (22). The cleaning device has valve elements (23) that are controlled by an electronic controlling and/or regulating device. The valve elements and regulating device are formed such that the nozzles supply the cleaning liquid to section areas (24, 25) within a defined time interval during cleaning operation of an inner area of the liquid tank.
