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Butterfly check valve is suitable for water, sewage, oil and gas and other media, widely used in municipal water supply and drainage, chemical industry, fire fighting and HVAC systems. Its structure is compact, rapid opening and closing, suitable for low-pressure working conditions, the working temperature is generally 0 ℃ to 150 ℃. The valve plate realizes one-way control of medium flow direction through rotation, prevents backflow and protects the safety of pipeline network. Valve body materials commonly used include ductile cast iron, stainless steel and carbon steel, sealing materials are mostly rubber or fluorine plastic, with good corrosion resistance and sealing performance, easy maintenance and long service life.