A device for controlling the flow of plastics material, heated until flowable, through a housing, in particular a filtering device or a direction-control device for the plastics material, comprises a flow channel extending through the housing, and a plunger of circular cross-section longitudinally displaced in a bore of the housing transversely to the longitudinal direction of the flow channel. The plunger crosses the flow channel. An unslotted scraper ring is mounted outside the housing on a portion of the plunger projecting from the housing and is held by a stop so that the plunger is displaceable relative to the scraper ring. The inner diameter (d2) of the scraper ring is smaller than the diameter (d0) of the bore of the housing and also smaller than the diameter (d1) of the end of the plunger portion remote from the housing in the coldest operating state of that plunger portion. The scraper ring is always pretensioned on the plunger portion and therefore reliably scrapes off leaked material adhering to and carried by the plunger when the latter moves out of the housing.