Device for separating airborne particles into grain size classes

A device is described for separating airborne particles into grain size classes. The principle characteristic of the present invention lies in the fact that it comprises: a first base body formed as a cup in which there are formed three chambers which are upwardly open and in each of which there is created in use a depression with a respective predetermined value; a first channel formed in a second upper body, of substantially L-shape form and having a first cavity into which filtered air flows in use, and a second cavity facing the entrance of the said chamber communicating by means of a sharp curvature with the said first cavity; and a nozzle positioned in the said first cavity and operable to inject into it a quantity of particle-bearing air in such a way that the particles of dust present in this are sub-divided into various grain size classes in dependence on the aerodynamic diameter thereof, to flow into the said chamber in quantities which are a function of the difference of the various values of the pressure existing in these.