Study On Principle And Technology Of Halon 1301 Concentration Measurement Based On Infrared Absorption

With the procedure of the social and economic development, aircraft is becoming one of the most convenient transportation in our daily lives. The number of accidents of aircraft caused by cabin fire increases dramatically at the same time. Aircraft fire extinguishing system is one of the necessities to ensure its safe operation. The fire extinguishing agent concentration measurement system provides a key testing tool for the evaluation of the performance of fire suppression system. At present, the fire extin-guishing agent concentration measurement system used in China relies totally on equip-ment leased from abroad, which is of high cost and long lease periods. Therefore, the study on principle and technology of Halon 1301 concentration measurement based on infrared absorption is beneficial for the independent research and development process of aircraft fire suppression system in China.In this paper, we made a theoretical analysis of fire suppressant agent concentra-tion measurement approach based on infrared absorption method. The optical structure and data processing methods were designed, and the calibration of the equipment and performance analysis were also conducted. This study demonstrates the feasibility of infrared Halon 1301 concentration based on Lambert-beer law. According to the com-parison of infrared absorption spectrum of Halon 1301, carbon dioxide and water vapor, the absorption peak at 8.310μm was selected, and the theoretical derivation formula was performed. The optical system, data acquiring and signal processing system, and cal-ibration system were designed in this paper. The selection of components and their parameters were introduced. It shows that this device is capable of real-time measuring of Halon 1301 concentration in the volume fraction range of 0% to 25%. The resolution was 0.15%, the accuracy was ± 5.4% F.S., and the temporal resolution was 4ms.In order to reduce the error of fire suppressant agent concentration measurement device, and expand its application in real fire scenario in aircraft cargo, the experiment regarding the effect of temperature and humidity of mixed gas on the calibration curve was conducted. The results showed that the change of temperature of mixed gas has a more significant impact on the calibration curve. The experimental results of voltage ratio versus Halon 1301 concentration relationship show that the voltage ratio drops sig-nificantly as temperature rises from 25℃ to 100℃. But, the effect of relative humidity of mixed gas on calibration curve is not significant.