The utility model relates to a valve device technical field discloses a booster quick action emergency valve, velocity of flow detection mechanism that it includes the butterfly valve, be connected with the butterfly valve and close valve drive, power transmission element. The pass valve drive and the manual worm gear case of butterfly valve both sides are connected with the valve plate subassembly through weight end valve axle and roller box valve shaft respectively. Velocity of flow detection mechanism's velocity of flow detection arm and detection arm counter roll pass through the activity of power transmission element control stop pin axle with the effort that detects. It includes that support mainboard, one end are equipped with the movement weight rod of weight and set up buffering subassembly, movement weight rod stop device and the stop pin axle on the support mainboard to close valve drive, movement weight rod stop device respectively with stop pin axle and movement weight rod on the whereabouts and the location of weight lever pin shaft fit control weight. The utility model discloses a butterfly valve is the trip valve, full latus rectum direct current channel, and the flow resistance is little. Adopting pure machinery to rely on oneself and driving pass valve actuation work, simple structure is reliable. The falling speed that adopts buffering component control weight prevents to produce pass valve water hammer.