Patent ID: 8277707

Claim:
A method of operating a rotary tablet press comprising a housing, a rotary die table having a number of dies arranged circumferentially, each die being associated with at least a first punch having a first end receivable in the die through an opening of the die and arranged for compression of a powder or granular material in the die by reciprocation of the first punch, at least a cam for cooperation with a second end of the first punch in order to effect axial displacement of the first punch by rotation of the die table, each die opening and corresponding first punch end are enclosed in a compression chamber, said compression chamber comprising at least one dust extraction nozzle communicating with a dust ex-traction tube located outside the compression chamber, and said compression chamber communicating with surroundings of the tablet press through a pressure controlled non-return valve, wherein the non-return valve is arranged to allow air to enter the compression chamber and to prevent outflow from the compression chamber to the surroundings of the rotary tablet press, the method comprising: opening said pressure controlled non-return valve when a pressure inside the compression chamber is smaller than a pressure at the surroundings of the tablet press, and closing said pressure controlled non-return valve when the pressure inside the compression chamber is larger than the pressure at the surroundings of the tablet press.