Closed gas exchange speed-adjustable protective cap

The invention discloses a closed gas exchange speed-adjustable protective hat in the technical field of protective articles, comprising: a hat body comprising a hat shell, a hat brim, a PVC soft glass hood connected to the bottom of the hat brim, and a waistcoat connected to the bottom of the soft glass hood; the CO2 concentration meter assembly is used for measuring the concentration of CO2 in the PVC soft glass hood; the gas digital flow meter is used for measuring the change of wind power outside the closed protective cap; the digital differential pressure sensor is used for measuring the air pressure in the PVC soft glass hood; the air inlet and outlet assembly is used for realizing air exchange inside and outside the PVC soft glass hood; the mainboard assembly is composed of a driving circuit and a digital signal sampling circuit and arranged on the brim, the driving circuit is electrically connected with the digital signal sampling circuit, and the digital signal sampling circuit is electrically connect