7 conveyors for powdered and granulated bulk materials; namely, vacuum-type, rotating screw or belt-type conveyors; mixing machines for the mixing and homogenizing of granulated or powdered materials; extracting machine for the extraction of test samples or granulated or powdered materials stored in silos or bins; valves; namely, slide valves, flap valves, diverter valves, and rotary valves and air filters forming part of the aforesaid machinery; pumps and blowers for the pressure-conveying of granulated, powdered and fluid materials through pipes, tubes and hoses; air compressors; mechanical dust collectors; and mechanical elutriators