The invention relates to a novel low-
pressure triggering pressure lever
instability shut-off valve, which comprises the following main components: a valve body, a
valve seat, a valve clack, a rotating shaft, a valve cover, a valve rod, a spring, a
piston, an air cylinder, a slender rod, a rod cage, a rod cap and the like, wherein the slender rod is a triggering component for shutting off a valve, and is designed according to the principle of pressure lever
instability. When the pressure in a pipeline is higher than a specified point, a supporting force borne by the slender rod is lower than the pressure lever
instability critical load of the slender rod, a pressure lever is kept stable, a valve clack catch is clamped at the lower end of the valve rod, and the valve is kept to be in the open state. When the pressure in the pipeline is lower than the specified point, the
axial load borne by the slender rod exceeds the pressure lever instability
critical load of the slender rod, the pressure lever is instable, the
effective length of the pressure lever is instantaneously reduced, and at the moment, the valve clack catch is separated from the lower end of the valve rod, the valve clack rotates around the rotating shaft under the action of gravity, and the valve is closed under the push of fluid. The valve is simple in structure, is only provided with three moving components, and is very higher in reliability.