In a steam trap comprising a seat valve that is adapted to be switched over between an open position for a first discharge state with large throughput and a closed position for a second discharge state with small throughput, the closure element and the seat of the seat valve define, at the closed position, a two-part passage, said passage having a jet cross-section, which first decreases in size in the discharge direction and, subsequently, re-increases in size, and being delimited by the seating area, the sealing face and at least one, only local control groove in the sealing face and/or the seating area. In the aseptic double seated valve the steam trap serves to carry out a flushing cycle as well as a sterilization cycle in a filling plant.