Protective device of bag-type dust collector

The utility model relates to a protective device of a bag-type dust collector. By adopting the protective device, zero leakage is fundamentally achieved, failure or burning-out of a filter bag is avoided, the bag-type dust collector is ensured to operate normally, therefore, gas discharge during device operation is less than the atmospheric pollutant comprehensive discharge standard of 50mg/m , and the requirement on environment protection is met. The protective device of the bag-type dust collector comprises a cylinder, a cylinder support, a gas outlet pipe, a gas inlet pipe, a valve plate base, a double-valve-plate labyrinth device, a cylinder lengthening bar and a housing, wherein the cylinder is coaxially arranged above the housing, and the cylinder support is arranged between the cylinder and the housing; the cylinder lengthening bar is coaxially arranged below the cylinder in the housing, the double-valve-plate labyrinth device is arranged at the lower end of the cylinder lengthening bar, and the valve