The main function is to automatically give an audible and visual alarm when the concentration of harmful gas exceeds the standard, cut off the gas pipeline, stop gas supply, start the exhaust fan, and discharge harmful gas to prevent poisoning accidents. The non-full range gas detector consists of a sensor and a controller. The sensor is responsible for detecting the concentration of various combustible gases, while the controller controls the operation of the tripping device and the acousto-optic alarm device.