The low-resistance backflow preventer is a hydraulic control combination device developed by our company that is mainly used for water supply units such as urban water supply to strictly limit the pressure water in the pipeline to flow only in one direction. Its function is to occur in the water supply system. During siphon reflow and back pressure reflow, it can effectively prevent the medium with poor water quality at the outlet from flowing back to the inlet with better water quality, avoiding water pollution from domestic water, and ensure the safety of domestic water to achieve the purpose of avoiding backflow pollution. .