Generally speaking, the tunnel is a kind of building structure closed by itself, its own environment is more complex, and the ventilation and drainage equipment is not perfect. In addition, the influence of the environment in the subway tunnel on the rails and accessories laid in it is long-term. According to the existing main research, the main components of the gas in the tunnel are 78% nitrogen, 15% oxygen, 1.5 carbon dioxide, 0.28 combustible gas and other gases. What is important is that the concentration (volume fraction) of harmful gas in the tunnel is positively correlated with the passing rate of trains passing through the tunnel. Moreover, due to the redundancy of the tunnel, the internal gas distribution and temperature and humidity are uneven, the environment of each tunnel section is quite different.

As the main traffic mode of a city, urban rail transit has the characteristics of large carrying capacity, safety, punctuality, high efficiency, energy saving and urban land use. But up to now, how to do a good job in the subway tunnel internal environmental quality monitoring has not yet got a complete solution, because the train in the tunnel running environment research is relatively small, so now some of the equipment is not able to real-time monitoring to the tunnel environment, and then for the tunnel environmental monitoring and other research data are relatively lacking. In order to better grasp the operating environment of the tunnel section, it is necessary to equip the tunnel with a complete environmental parameter monitoring system for real-time measurement, and finally get the corresponding data of various environmental parameters, such as temperature, humidity, carbon dioxide, oxygen, flammable Gas, PM, etc.

    Here, only for the detection of oxygen, we recommend using the fluorescent oxygen sensor generated by the British SST. It is not only compact, but also very convenient in installation, use, communication and other aspects. It supports low-voltage power supply and has low total power. You can also use batteries. For developers, the data flow and programming and standby modes provided are quite flexible and practical. In addition to measuring oxygen concentration, it can also detect the temperature and humidity of the environment at the same time, allowing UART communication, mainly outputting TTL level signals of 3.3V, and supporting USB or RS232. There are three kinds of ordering information provided, one is diffusion-through type, the other is bottom-sealed diffusion measurement, and the other is air extraction or ventilation test with snorkel type. The sensor series covers a large area and can be applied to many different scenes and practical applications. Of course, British SST also accepts various customizations with large demand.