In the inertial impact dust collectors, it is possible to decrease water consumption to the great extent. The possibility of periodical water replacement and ability to immediate operation in case of sudden dust loading enable water requirement minimization. For the one-directional turbulent washer with the impeller the gas velocity and water level have been established which guarantee high collection efficiencies with pressure drop less than 1800 Pa. Fractional collection efficiency has been established for test dusts. The critical particle size is less than 1 mu m also for soot (non-wettable) particles. The apparatus has been utilized to measure the critical recirculation factor, which will be presented in the Part II of this paper.