An extraction device for discharging a mixed fluid, in particular containing feces, from a collecting tank of a rail vehicle comprises a housing having a mixed fluid inlet and a mixed fluid outlet, a flow passage which extends in the housing between the inlet and the outlet, a retaining latch mounted to the housing and adapted to cooperate with a corresponding recess on the collecting tank and is pivotably reciprocal between a locked position and an unlocked position, a shut-off member reciprocable between a release position and a blocking position, and a handling means or actuator mounted to the housing for actuation of the shut-off member. The handling means is operatively connected to the retaining latch in such a way that upon the movement of the retaining latch into the unlocked position the shut-off member is put into the blocking position.