Penetrometry through a cone is a standardized method of comparing the consistence of semisolid systems. For the time being, this arrangement is only of marginal importance for the evaluation of flow ability of powders. For this purpose it is recommended to use penetrometry by means of a ball, which is significantly connected with the volume flow rate. The present original paper attempts to find the regression dependence suitable for the estimation of the flow rate of size fractions by means of powdered auxiliary substances. This solution replaces the traditional penetrometric degrees (unit of length) with volume or weight of freely layered powder pushed out by the penetrating ball. The optimal method is the transformation of penetrometric degrees to the weight of the powder, which makes it possible to estimate the weight rate of pouring with the use of an exponential equation elucidating 97.4 % of total dispersion. Penetrometry with the use of a ball could be included into the group of tests for the evaluation of flow ability and structure of powdered auxiliary substances.

        Key words: powders – flow rate – penetrometry