This slow closing check valve is a hydraulically diaphragm-type driven automatic control valve.When the upstream pressure of the valve is greater than that downstream of the valve, the valve will open fully. When the upstream pressure of the valve is less than that downstream of the valve, the valve will close tightly to prevent backflow. Both the opening and closing speeds of the valve can be controlled and adjusted on-site. It is mainly used in urban water supply and drainage, building water supply, fire water, industrial water and other occasions.