This Venturi pump (2), which can be used for sucking powder from a supply (A), diluting same, then feeding it to a gun (D) via a conveyor pipe, comprises an outer body (20), at least one powder suction duct (22), at least two air connections (24, 28), of which a first air connection (24) is capable of supplying an injector (284) to create a vacuum inside the suction duct (22) and a second air connection (28) is capable of supplying a dilution air circuit separate from the powder flow, at least one powder outlet nozzle (26), centred on an axis of diffusion (Y26), the inlet of which is located downstream from the first air connection (24) and the suction duct, at least one protection barrier (282), disposed inside the dilution air circuit and at least one outlet tip (284) of the dilution circuit, disposed around the nozzle (26) and also connected to the conveyor pipe (T). The protection barrier comprises a non-return valve (282) that radially surrounds the nozzle (26).