Monitoring System Of Air Quality In Closed Environment

There are many special dense living environment in the field of industrial and military, such as mine rescue capsule, specific seal workshop, underground fortifications, submarines, etc. The common feature of these environments is that the confined space is small and it doesn't flow with the outside world. With its accumulation of the human activities, it will pollute the environment and it will produce nausea, dizziness, weakness and other symptoms if one stayed in that environment for long time. For this, developing a monitoring system of air quality in closed environment has theoretical significance and great value.Based on the study on a large number of relevant literature and related standards about monitoring system of air quality in closed environment, it proposed a scheme based on modular measurement. The system uses a distributed power scheme, it uses the isolated DC/DC switching power supply LT3748 as the core, and AMS1117,TL431 is added. The system consists of main board and measuring board. Measuring board is responsible for the measurement of gas-related parameters. Main board is responsible for collecting the gas measurement plate measuring parameter values. When tested environment changing, one just need to do is add or subtract the appropriate measurement board. This increases the flexibility of the system and post ease of maintenance.The main board and measurement board use the UART to communicate. CRC check enhanced the reliability of data transmission. It studies the measurement principle of the electrochemical sensors, temperature and humidity sensors and differential pressure sensors in this paper. It designed signal measurement circuits, RS485 and 4-20 m A output interface circuits and using a piecewise linear approach to improve the nonlinear problems of the sensor. Considering the ease of use of field personnel, it established evaluation model and software implementation based on the theory of fuzzy mathematics about the evaluation ofthe monitoring system of air quality in closed environment in this paper.A preliminary measuring experiment was implemented after the system is completed. The experimental results show that the measurement results achieve the relevant standards and it has the practical value.