Gas leakage calibration instrument

The utility model relates to the technical field of gas leakage calibration instruments, in particular to a gas leakage calibration instrument which comprises an instrument outer shell, a gas inlet is formed in one side of the instrument outer shell, an overhaul shell is installed on the left side of the base plane of the instrument outer shell, a transparent window is installed on the base plane of the overhaul shell in an embedded mode, and a gas outlet is formed in the left side of the transparent window. A controller and an alarm are embedded in the right side of the base surface of the instrument outer shell, a calibration equipment body is arranged in the instrument outer shell, a radiator is arranged above the calibration equipment body, and an air suction fan is arranged between the inner wall of the left side of the instrument outer shell and the left side of the calibration equipment body; when internal elements of the gas leakage calibration instrument are overhauled, the overhauling shell on the o