If the throttle valve in a significant reduction in the state, the valve plate on the back prone to cavitation, there is the possibility of damage to the valve, generally used in the 15 ° outside. When the valve is in the opening, the opening shape of the front end of the body and disc formed in the valve shaft as the center, forming a complete worm gear on both sides of a different state butterfly, the butterfly plate along the flow direction of the front side of the wings, the other side of the counter-current water moving direction, and therefore, the side of the body and the valve plate is formed like a nozzle-shaped openings, similar to the other side of the orifice-shaped openings, fast nozzle orifice side side than the flow rate, and the throttle valve below will produce negative side often there will be a rubber seal off. Valve operating torque, due to open and close the valve opening and its value varies in different directions, horizontal elastic butterfly valve, especially large-diameter valves, due to water depth, valve shaft, the torque generated by the water head difference can not be ignored. Further, when the inlet side of the valve means bend to form a bias current, torque will be increased. When the valve opening in the middle, because the water flow torque to work, organizations need to operate self-locking. First, due to the multi-Flex stacked ring fixed in the marine butterfly valve plate, when the valve plate normally open state media to form a positive sealing surface erosion, erosion after the butterfly, the direct impact of the soft metal sheet sandwich seal by sealing performance. Second, the structural conditions by limiting the structure do not meet the following diameter DN200 slow closing valve butterfly valve plate because the overall structure of thick, large flow resistance. Third, because the principle of the three eccentric structure, the sealing surface of the seat between the valve plate by the transmission of torque to the valve plate is pressed against the valve seat. Positive flow state, the higher the pressure medium sealed tight squeeze. When countercurrent flow medium with medium pressure increases between the valve plate and seat when positive pressure is less than medium pressure, the seal began to leak. Slow closing valve, Yunfu butterfly valve provided by the Hong Kong Ming Ming Port Valve Co., Ltd., Dongguan. Port Valve Co., Ltd., Dongguan Ming (www.gdmgfm.com) strong, credible, butterfly and other industries in Dongguan, Guangdong has accumulated a large number of loyal customers. The company better work attitude and constantly improving innovative ideas will lead the next port of the valve and you hand into the brilliant, for a better future!