Disclosed are topical antimicrobial compositions. In order to make the connection such that it can be produced simply and accurately, and to make it quite tightly, on the side of the annular bead facing the pipe connecting piece, the pipe forms a cylinder with two circumferential grooves, in each of which a sealing ring is seated, which rests in a sealing manner on the cylindrical inner surface of the pipe connecting piece. These contaminant gases are emitted with nitrogen gas, which is used in operation of a dry pump.