Abstract: Abstract: This paper presents a new automatic emulsion system used in coal mine based on PLC. The system mainly uses the jet pump and explosion-proof solenoid valve, combined with the level sensors and concentration sensor combination to achieve the function. Two sets of liquid distribution solution are designed, the concentration ratio and the ratio of total volume method,so that the automatic liquor can be realized adaptively. Through to acquire and process the sign, the function of intelligent fault diagnosis are developed, and the undisturbed switch between the two liquid distribution solution can be achieved when failure , then the availability and stability of the system are improved.Since the system was put into use, it has achived good effect.

Key words: Automatic liquor, jet pump, Volume ratio method Filtering, The filter