the air shock tank (7) is filled with compressed air. At a preset or automatic time, the pump and the conveying are stopped and the bottom valve (2) is opened. The product is discharged at the same time as the air shock is activated and the compressed air cleans the filter from dust and small particles. When the pump starts again, this process is repeated and a new cycle starts. The suction time and emptying times are normally controlled by a pneumatic, an electric control system or completely automated with the new smart systems.