The function of American standard check valve is to control the one-way flow of medium in the pipeline, used to prevent the backflow of medium in the pipeline. The design and manufacturing of the product comply with American standards. The check valve belongs to the automatic valve category, and the opening and closing parts are opened or closed by the force of the flowing medium. Check valves are only used on pipelines with unidirectional flow of media to prevent backflow and prevent accidents. Mainly used in pipelines for petroleum, chemical, fertilizer, electricity, and other industries.