Check valve is an automatic opening and closing valve for water, steam, oil, gas and corrosive media, widely used in petroleum, chemical, electric power, metallurgy and other systems to prevent media backflow. Suitable for horizontal or vertical pipelines, commonly used in pump outlets and other key positions. The working temperature range is generally -29℃ to +550℃, depending on the material. The main function is to use the medium's own flow pressure to automatically open or close the valve to prevent backflow. Commonly used materials include carbon steel, stainless steel, alloy steel, sealing surface can be selected stainless steel or hard alloy, to adapt to a variety of complex working conditions.