When pumping medium consistency stock (8 to 15%), a plug flow is generated in the pipe. At normal flow velocities, the fiber network holds the plug flow together. Dividing this kind of flow into precisely controlled partial flows at the end of a pipeline using valves alone is almost impossible, since the high consistency creates a risk of clogging. A similar risk may also occur when stock must be discharged into a pipe through a contraction, for example at the top of a bleaching tower.