High -low pressure switching device of well head safety automatic analysis line valve

The utility model discloses a high -low pressure switching device of well head safety automatic analysis line valve contains output end cover, cylinder body and input end cover, and output end cover,input end cover install respectively in the cylinder body both ends, is provided with output plunger and input plunger in the cylinder body, closely laminate between output plunger and input plunger and the cylinder body inner wall, be provided with the dowel steel between output plunger and the input plunger, form hermetic cavity room no. 1 between output end cover, cylinder body, the output plunger, form hermetic cavity room no. 2 between output plunger, cylinder body, the input plunger, form hermetic cavity room no. 3 between output end cover, cylinder body, the output plunger. The utilitymodel discloses a cooperation of two plungers and three cavity, this device can be according to the arbitrary set pressure value range of user's needs to more effectively guarantee well head safety shut -off valve's normal ope