Worm gear wafer butterfly valve, usually used in size big than DN250, The worm gear box can increase the torque, but it will slow down the switching speed. Worm gear butterfly valve can be self-locking and will not reverse drive. For this Soft seat worm gear wafer butterfly valve, the advantage of this product is that the seat can be replaced, which is favored by customers. and compared to the hard back seat, its sealing performance is superior.