Filter for ventilation system outside closed gas hood

The utility model discloses a closed gas hood outer ventilation system filter which comprises a shell, the top of the shell is fixedly connected with a connecting pipe communicated with the shell, the tail end of the connecting pipe is fixedly connected with a closed gas hood communicated with the connecting pipe, a through opening is formed in the shell in a penetrating mode, a sealing plate is installed in the through opening, and the sealing plate is fixedly connected with the closed gas hood. An activated carbon filter screen is fixedly connected to the rear end of the sealing plate, the left end, the rear end and the right end of the activated carbon filter screen abut against the inner wall of the shell, a cleaning mechanism is arranged in the shell, an air supply mechanism is arranged in the shell, and two dismounting and mounting mechanisms are arranged between the sealing plate and the shell. According to the utility model, the filter screen can be taken out by arranging the dismounting mechanism, an