Air inlet device used for fermentation tank and capable of preventing materials from flowing backwards

The utility model discloses an air inlet device for a fermentation tank capable of preventing materials from flowing backwards. The guide pipe is arranged in the tank body, the alarm is arranged on the top of the surface of the tank body, the controller is arranged on one side of the surface of the tank body, a buzzer is detachably connected to the surface of the alarm, a light-emitting warning lamp is arranged on the surface of the alarm, and a pressure gauge on a filter is replaced by a pressure transmitter. A front check valve arranged in a guide pipe on the surface of the tank body is replaced by a pneumatic diaphragm valve, the pressure transmitter and the pneumatic diaphragm valve are subjected to linkage control through a controller, and when the controller detects abnormity in the guide pipe and the pressure of the air pre-filter is smaller than the pressure in the tank body, a system in the controller automatically judges, and the pneumatic diaphragm valve is started. The pneumatic diaphragm valve is