Modular devices for the extraction of fumes

Improvements to smoke-extraction apparatus and ventilation apparatus for buildings allowing to assure a better steadiness of a depression factor at an opening of smoke ducts or ventilation ducts of buildings under an effect of different winds, falling or rising, by way of a modular device including

• a base element essentially formed by a ring of a general external truncated-cone form, which base element is placed at an orifice of smoke ducts;
• one of a static member and mechanical ventilation elements associated to the base element, wherein the static member surmounts the base element and which static member constitutes a static module capable of providing an underpressure in said smoke ducts under only an effect of wind, which sweeps through the modular device, wherein the mechanical ventilation elements are formed by an opened centrifuge turbine driven by an electric motor and forming a dynamic module capable of creating a necessary air current alone or supplementing the wind in order to assure a higher depression in connection with said base element, wherein the base element creating a footing (2) has a continuous and smooth contour curve when considered in a sectional view of the footing, wherein the continuous and smooth curve exhibits an upper bulge and a lower bulge, and wherein an area of the upper bulge assumes from about 0.25 to 0.33 of a vertical extension of the footing from a top of the footing, and wherein an area of the lower bulge assumes from about 0.67 to 0.75 of the vertical extension of the footing from the top of the footing, wherein a maximum thickness of the upper bulge is from about 0.01 to 0.02 times the vertical extension of the footing, and wherein a maximum thickness of the lower bulge is from about 0.05 to 0.1 of the vertical extension of the footing.