FREE-VALVE pneumatic tungsten carbide double disc balance gate valve is mainly used in feeding and dumping the dry powder and the transport pipeline, which not only adopt toughening tungsten carbide as shut off and wear out resistance material, but also design construction of pressure self-sealing and valve disc auto-rotate, so as to the sealing surface within the dry powder get more wear resistance in process of opening and closing frequently, thereby, which guarantee the high requirements of sealing performance of this valve and long working time.