Thanks to the material flow control and the limitation of the largest grain size by the intermediate diaphragm, the material stays in the first grinding compartment until it reaches optimum size; only then it moves into the second compartment. The separation of air and material flow, a major development by Christian Pfeiffer, ensures that so-called dead zones (zones without material being ground) directly behind the intermediate diaphragm are avoided. The result is a clearly more efficient grinding process