| Photo Ionization Detector (called PID) is a detector with high sensitivity and a far-ranging uses, it can detect volatile organic compounds and other poisonous gas. Compared with traditional detective methods, it has the advantage of portable type, high accuracy (ppm magnitude), fast response and continuous test and so on. Photo Ionization Detector is widely used in in Aviation and Aerospace area, Environmental Monitoring, Chemistry and Chemical Engineering , Rail transport, Motor Transport and so on. especially in leak detection in disaster area's accident and aerospace fuel, flammable and explosive VOC detection.This paper introduces the foundamental knowledge and the basic structure of Photo Ionization Detector, the good results and shortage during the initial research period in brief. We also have done some research to work out high zero shifts, low resolution, unreliability of Photo Ionization Detector. The improvement in material, structure and encapsulation of Ionization chamber are illuminated in detail, also include the improvement of power system design and weak signal (pA) detection cicuit based on electrometer amplifier OPA128. The paper also introduces linearization algorithm, oversampling, digital filtering, design of anti-jamming in the end. According to National Standard for Explosion Protection and sensor's special application environment, the flameproof enclosure is designed, the authority of The State issue explosion proof certificate, and the relevant design about explosion protection, waterproof, dust prevention. After completing the system integration of the Photo Ionization Detector, reliability test and calibrating test is carried on in space propellant research center, and the results show that basic Indicators of sensor is improved obviously.The optimal Design of Photo Ionization detector is completed in this paper. At the same time the high price and cost of the Photo Ionization sensor are also reduced. It is a very important step for promoting its market process. |
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