| Summary: | One of the main reserves for increasing grain production is the use for sowing high-quality seeds, purified from impurities and pathogens. One of the main ways to protect the seed from various diseases is dressing. The most effective way to protect seeds from disease is wet dressing with the simultaneous release of grain impurities. To develop a device for cleaning and dressing seeds by density using a wet method, an estimate was made of the minimum height of the fall of the grain needed to overcome the surface tension of the liquid. As objects of research, pea seeds were used, having a shape close to a spherical. Therefore, a spherical grains with a density ρz = (1.15-1.45)·103 kg/m3 and a diameter of 2rz = (3.5-10.9)·10-3 m was taken as a model of pea seed. We study the fall of individual spherical grains with minimal (2rzmin = 3.5·10-3 m) and maximum (2rzmax. = 10.9·10-3 m)) linear dimensions that have a density ρz = 1.15; 1.25; 1.35 and 1.45·103 kg/m3. Drop occurs on the surface of the water (ρzh = 1.0·103 kg/m3) and the aqueous solution of the etchant (ρzh = 1.03; 1.06; 1.09; 1.12 and 1.15·103 kg/m3), with Corresponding coefficients σ of surface tension (0.0727; 0.0755; 0.0771; 0.0786; 0.0801, 0.0816 N/m) and hydrodynamic drag coefficients c = 0.4 (0.5 for ρzh = 1.12·103 and 1.15·103 kg/m3). The process of dressing grain is considered at a temperature of 20 °C. It was established that the minimum drop height h to overcome the surface tension of the dressing solution with all spherical grains should be 15.5·10-3 m.
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