Measurements of Gaseous Toluene Concentration with a Semiconductor Gas Sensor

• Main Authors: Sun Yueh-Wei, 孫岳瑋
• Other Authors: Liu Shi-Ping
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/64vxsq

碩士 === 輔仁大學 === 公共衛生學系碩士班 === 99 === In recent years, the prosperity of industrial activities gradually increase the use of organic solvents, resulting in abundant amount of emissions and subsequent pollution. Volatile organic compounds （VOCs） easily escape to the air. It’s not only harmful to human health, but also tended to the workplace explosive accidents. Therefore, developing a economic and effective sensing element to monitor the VOCs in the workplace is necessary. In this study, we evaluated a semiconductor-type sensor to detect toluene which is the the largest use solvent chemical in Taiwan. The first setting of the experiment is to develop a stable airflow and criculation exposure chamber system. The target toluene concentrations were set to 13, 65, 110, and 209 ppm and simultaneously monitor the sensor’s response for the effectiveness test. In the assessment, laboratory temperatures were contorlled to about 26℃ and humidity to about 55%. Furthermore, we also used infrared lamp to maintain temperature around the chamber to prevent VOC condensation. This study results show the toluene concentration distribution is well mixed in the chamber. The semiconductor sensor can detect toluene effectively in 12 minutes after its cold start. It voltmeter signal increased as toluene concentration elevated to the toluene concentration of 209 ppm. Finally, the upper detection limit of the semiconductor sensor was examined about 1,000 ppm of toluene. This study concluded that the semiconductor-type sensor TGS-2602 can be used in detecting toluene gases effectively in working environment. Its instant response and detection linearity falls within an acceptable margins of 5%. Further evaluations of the semiconductor sensor were suggested in climate changes, salt corrosion and so on. The explosion tendency of such semiconductor-type sensor should be thoroughly investigated before its field application in the refinery industries.