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This paper is aimed at the actual conditions of disaster caused by gas in small and medium-sized coal mines. A new gas concentration monitoring system for coal mines is developed on the basis of gas-sensing detection and singlechip control.The monitoring system uses the tin oxide as the main material of N-type semiconductor gas sensors,because it has good sensitive characteristics for the flammable and explosive gas(such as methane,carbon monoxide). The QM-N5-semiconductor gas sensor is adopted to detect the output values of the resistance under the different gas concentrations. The system,designedly,takes the AT89C51 digital chip as the core of the circuit processing hardware structure to analyze and judge the input values of the resistance,and then achieve the control and alarm for going beyond the limit of gas concentration.The gas concentration monitoring system has many advantages including simple in structure, fast response time,stable performance and low cost.Thus,it can be widely used to monitor gas concentration and provide early warnings in small and medium-sized coal mines.
This paper is aimed at the actual conditions of the disaster caused by gas in small and medium-sized coal mines. A new gas concentration monitoring system for coal mines is developed on the basis of gas-sensing detection and singlechip control. tin oxide as the main material of N-type semiconductor gas sensors, because it has good sensitive characteristics for the flammable and explosive gas (such as methane, carbon monoxide). The QM-N5-semiconductor gas sensor is adapted to detect the output values of the resistance under the different gas concentrations. The system, designedly, takes the AT89C51 digital chip as the core of the circuit processing hardware structure to analyze and judge the input values of the resistance, and then achieve the control and alarm for going beyond the limit of gas concentration. gas concentration monitoring system has many advantages including simple in structure, fast response time, stable performance and low cost.Thus, it can be wide ly used to monitor gas concentration and provide early warnings in small and medium-sized coal mines.