Hydraulic check butterfly valve is suitable for the medium of water pump outlet pipe, as a closed-circuit and check valve, used to avoid and reduce the pipeline system medium backflow and excessive water hammer to protect the piping system. The valve is driven by hydraulic drive, can be closed by heavy hammer, opening and closing flexible and reliable. After the pump is installed on the pump, it can replace the two valves of gate valve, butterfly valve and check valve. The flow resistance coefficient is only 30% of the rheological resistance coefficient of the two valves mentioned above. Therefore, this type of valve for energy-saving products. Close, the liquid control device sub-fast clearance, slow off two stages: the first 60 ° for the fast off, after 30 ° for the slow off, according to different conditions, the speed can be adjusted off the time and fast, slow and change the angle to prevent A big water hammer occurred. The valve also has dwelling function: the butterfly valve hydraulic system reset with accumulator, build pressure oil, supplement the system of leakage, and can automatically fill pressure. At the same time with automatic reset function, when the valve opening decreases (hammer drop) 15 °, the pump starts, automatic reset. Standby reset device, the butterfly valve is opened, when the hydraulic system appears a trace of leakage accumulator supplement, the pressure drops to a certain value, the relay to make up pressure, slightly prevent the pressure relay failure, with travel switch reset device, that is, in the The valve opens the position of Paul and Paul double-bit protection.