For further investigations on the ignition process of dust/air mixtures and for improvements on the testing system it is important to analyze the particle dispersion and flow properties of the 20 liter apparatus more in detail. The normed 20 liter SIWEK apparatus was modeled in OpenFOAM and the simulation results were compared to literature data. To disperse dust in air under reduced pressure properties it was necessary to implement a rotor – stator system. To design this system a simulation was set up which models the rotating disk with a stator and the flow conditions in it. With this simulation it was possible to develop the geometry of the rotating disk system step by step and offer a buildable system at the end. The final geometry was modeled under various operating conditions and data of dust dispersion and turbulence were extracted from the simulation. These two properties are very difficult to measure in the lab test but they are easy to calculate in simulation. The results of the new designed dispersion system show a more homogeneous dust and turbulence dispersion like using the standard dispersion system.