A detailed 2D model of SiH4-H2 discharges was implemented in order to investigate the effect of the total gas pressure and flow on the SiH4 consumption and depletion. Simulations of an industrially relevant medium scale reactor were carried out and the results were compared to experimental measurements of silane depletion in the center of the plasma and consumption in the exhaust port of the reactor. The limited electron – SiH4 dissociation rates, due to short residence times or low electron – molecule collision frequencies (high flows - low pressures), result in reduced silane consumption and depletion. This indicates that a first step in optimizing SiH4 consumption should be to maximize the electron population with sufficient energy to dissociate SiH4 towards neutral species. This can be achieved by tuning process parameters such as pressure and input flow. In addition, a good agreement between model and experiments for the effect of total gas pressure on silane consumption and depletion efficiency was found when SiH4 vibrational states reactions and particle formation reactions were included in the model. This underlines the importance of these microscopic processes on the mechanisms of SiH4 consumption and depletion and the deposition efficiency.