則武 祐二 (株)リコー品質管理部, 安全性推進センター, 2グループリーダー
砂金 光記 (株)リコー研究開発本部, 課長代理
HIGASHI Toshiaki University of Occupational and Environmental Health, Institute of Industrial Eco, 産業生態科学研究所, 教授 (10119000)
NORITAKE Yuji Ricoh Co., Group leader
ISAGO Kouki Ricoh Co., Associate Chief
|Budget Amount *help
¥4,500,000 (Direct Cost : ¥4,500,000)
Fiscal Year 1995 : ¥1,200,000 (Direct Cost : ¥1,200,000)
Fiscal Year 1994 : ¥3,300,000 (Direct Cost : ¥3,300,000)
Charcoal tubes are widely used for measuring organic vapors in work environments, but it is impossible to know the breakthrough of the vapors during the sampling. In this study, a detection method of organic vapors was developed by using semiconductor gas sensors.
Organic vapor was introduced into a glass column equipped with two sensors and the resistance of the sensors was monitored. After the system became steady state, a charcoal tube was attached to upstream of the sensors. The resistance of the sensors was collected temporally to an IC card. The vapor concentration of the exhaust air near the sensors was measured with a FID-gas chromatograph (GC) at intervals of 5 min to obtain the breakthrough curve.
When the relative humidity was 0%, output signals of the sensors began to change before the breakthrough was recognized for all of tested organic vapors, that is, acetone, methyl ethyl ketone, methyl acetate, ethyl acetate, methanol, IPA,toluene, 1-butanol, dichloromethane, chloroform and 1,1,1-trichloroethane. When the relative humidity was 80%, the sensors could also be detected the vapor before the breakthrough was recognized for many organic vapors, but the breakthrough of the vapor cannot be detected for dichloromethane and chloroform.
Based on the above results, an alarm system that can inform the breakthrough of a sampling device was developed. The developed system can detect the breakthrough of many organic vapors, so that it will become to be useful for an indicator of the sampling limit in charcoal tubes.