Design And Realization Of A New Type Portable Gas Detecting&Alarming Device

Nowadays, Safety in production of coal mine has been an important problem confronteddomestic and overseas mine industry. Gas explosion is one of most serious mine disasters, whichlead potential and great insidious danger to domestic coal mine industry. In order to largelyreduce personal Safety and economic loss brought by gas explosion, a new gas alarm ismeaningful. After investigation, most of gas alarms in domestic market have shortcomings suchas bulky, short service life and charge too often, etc. Aiming at these shortages, a new portabletype gas alarm with microcontroller has been designed out and proposed in this project research.This gas alarm can inspect and measure the gas consistency under an intermittent operationmode with using gas sensor. Normally inspection for gas consistency will be taken intermittently.If potential safety hazard being found, its gas sensor will be immediately turned into acontinuous operation mode, and gas consistency in air should be changed in electrical signals.Those analog signals will be converted to digital signals through AD-convertor, after beingproceed with microcontroller, and then gas consistency can be real time shown in7-segmentnumeric light emitting diode (LED) display. When the gas consistency exceeds the threshold ofsafety standard, the audible and visual alarm will be performed with utilization of audible&visual alarm circuit. This kind of intermittent operation mode can lengthen the duration of powerbattery, thus reduce its charging frequency, and can largely lower the alarm’s power dissipation,improve its service life as well. Moreover, according to its portable characteristics, the innerchipsets of this new designed gas alarm are all using surface mount type which bringsadvantages such as small volume, low power dissipation and accurate inspection&alarming.The flameless combustion air-sensitive semiconductor gas sensor was adopted which iscomposed of black&white elements, as well as ATmega48microcontroller. This design offershigh cost-efficiency and low power dissipation. According to its portable characteristics, theinner chipsets of this new designed gas alarm are all using surface mount type which bringsadvantages such as small volume, low power dissipation and accurate inspection&alarming.The software used in this paper was designed with modularization programming. Eachsubprogram module had been compiled in very detail, in order to make more explicit descriptionfor its process; the relevant flow chart was made accordingly.After both hardware and software being designed and manufactured, simulations&experiments on this gas alarm were carried out with satisfying testing results which can basicallymeet the requirements. This new type of gas alarm has been put into production, of which annualoutput is more than100000units, and obtains customers praise.