Infrared Absorption Method Co <sub> 2 </ Sub> Concentration Monitoring System Design And Build

The main gas concentration detection technology is reviewed. Firstly the traditional non-optical detection methods are briefly introduced, including titration, catalytic thermal, gas-sensing, electrochemical. Then the progress of infrared absorption analyzers of carbon dioxide is mainly discussed. A newly designed system that is based on non dispersive infrared measurement has been designed and made up for analyzing the concentration of CO2, working in side-stream way.6004 module serves as the core parts of the system for CO2 analyzing, micro control unit communicates with the module by the SPI protocol. I/O components, such as keys and LCD are used for controlling the device and displaying the messages, what is an advance for physical operation. Zero calibration, span calibration and several fixed points calibration are done for the system of CO2 analyzing. What's more, air-intake installation has been improved, what provides a controllable technique for imitating the change of CO2 concentration. Quantitative dilution and real-time measurement about CO2 concentration have been done, what is for fixed points monitoring and continuous monitoring of the system. Then the system's static and dynamic characteristic, and the repeatability are evaluated.According to the experiments, the monitoring system that uses the non dispersive infrared absorption principle and consists of 6004 module and micro control unit can achieve good results in case of frequently changing in CO2 concentration. The system is compact, easy to operate, and suitable for long-running.The monitoring system introduced in this paper has high capability/price ratio, it provides an effective means to real-time monitoring of carbon dioxide in clinical respiratory systems, having good prospect.