Abstract: The invention concerns a device comprising two components connected to each other with possible displacement of one component relative to the other, sealing means arranged between said two components, and flow rate adjusting means actuated by displacement of one component relative to the other. The invention is characterized in that the device comprises positioning means for placing the two components in two different positions, namely a first so-called sterilizing position, wherein said two components do not, or hardly exert, any stresses on the sealing means, and second so-called operating position, wherein said two components stress the sealing means to provide the required sealing conditions.