An apparatus has a plurality of inlet ports each connectable to a material supply container and an outlet port. A disk-shaped valve body has a first side and an opposite second side with a straight throughgoing passage from the first side to the second side, the body being displaceable relative to the inlet ports to provide a switchable connection between a respective one of the plurality of inlet ports and the outlet port. The passage can be also be connected with a respective one of the various inlet ports to enable feeding of different materials successively to the outlet port. One of the inlet ports is a flushing medium inlet port of a flushing device, and the passage can connected with the flushing medium inlet port by displacement of the valve body for flushing the passage.