A detecting device of at least a thermographic image, comprising a thermal camera sensitive to infrared radiation for acquiring the thermographic image, a protective case internally of which the thermal camera is inserted, the protective case exhibiting a window through which the thermal camera is able to acquire the thermographic image, the device comprising a screen arranged externally of the protective case and mobile between a first operating position in which it is superposed on the window so as to protect it from environmental disturbances and a second operating position in which it is shifted from the window so as to enable the thermal camera to acquire the thermographic image, a pneumatic air supply system internally of the protective case having an inlet that is external of the protective case, the device being characterised in that the pneumatic system comprises adjusting and distributing means of the air operatively active internally of the protective case and in communication with the external inlet, the means for adjusting and distributing the air comprising a plurality of solenoid valves in communication with the external inlet and a plurality of conduits in communication with the solenoid valves, the device comprising a computerised control and command unit of the solenoid valves, the means for adjusting and distributing comprising a first conduit (13a, 15) for blowing air internally of the protective case and cooling at least the thermal camera, and a first solenoid operatively active between the external inlet and the first conduit (13a, 15) for supplying air to the first conduit (13a, 15), the first solenoid being mobile between a first operating configuration at which the first conduit (13a, 15) is closed and a second operating position at which the first conduit (13a, 15) is open and in communication with the external inlet; said computerised control and command unit being configured such as to pilot the first solenoid between the first and second operating configurations; the device comprising a vortex tube interposed between the first solenoid (13 and the protective case, an inlet for compressed air of the vortex tube being in communication with the first solenoid and an outlet for cooled air of the vortex tube being in communication with the first conduit (13a, 15), the vortex tube preferably developing externally of the protective case. a thermal camera sensitive to infrared radiation for acquiring the thermographic image, a protective case internally of which the thermal camera is inserted, the protective case exhibiting a window through which the thermal camera is able to acquire the thermographic image, the device comprising a screen arranged externally of the protective case and mobile between a first operating position in which it is superposed on the window so as to protect it from environmental disturbances and a second operating position in which it is shifted from the window so as to enable the thermal camera to acquire the thermographic image, a pneumatic air supply system internally of the protective case having an inlet that is external of the protective case, the device being characterised in that the pneumatic system comprises adjusting and distributing means of the air operatively active internally of the protective case and in communication with the external inlet, the means for adjusting and distributing the air comprising a plurality of solenoid valves in communication with the external inlet and a plurality of conduits in communication with the solenoid valves, the device comprising a computerised control and command unit of the solenoid valves, the means for adjusting and distributing comprising a first conduit (13a, 15) for blowing air internally of the protective case and cooling at least the thermal camera, and a first solenoid operatively active between the external inlet and the first conduit (13a, 15) for supplying air to the first conduit (13a, 15), the first solenoid being mobile between a first operating configuration at which the first conduit (13a, 15) is closed and a second operating position at which the first conduit (13a, 15) is open and in communication with the external inlet; said computerised control and command unit being configured such as to pilot the first solenoid between the first and second operating configurations; the device comprising a vortex tube interposed between the first solenoid (13 and the protective case, an inlet for compressed air of the vortex tube being in communication with the first solenoid and an outlet for cooled air of the vortex tube being in communication with the first conduit (13a, 15), the vortex tube preferably developing externally of the protective case.