The technological process of materials grinding, especially biological material with high oil content, is quite complex. There are several parameters that impact the performance and quality of the process (e.g. temperature, rotational speed). One of them is the air velocity at pneumatic conveying of grinding particles. The phenomena of pneumatic transport of seeds and its impact on product’s quality and grinding capacity is not methodologically recognized so far.  The paper presents the construction details of measurement and control system and results of the research obtained during the laboratory tests.  The results of the tests and their analysis will be used for design of a commercial precise grinder, which allowed to reach the optimum product’s capacity and quality, constituting the basis for biological diet supplements.