Development of a new sampling device for hazardous gases and vapors in work environments with a built-in breakthrough detector using semiconductor gas sensors

木炭管被广泛用于测量工作环境中的有机蒸气，但在采样过程中不可能知道蒸气的突破。本文提出了一种利用半导体气体传感器检测有机气体的方法。将有机蒸汽引入装有两个传感器的玻璃柱中，并监测传感器的电阻。当系统达到稳定状态后，在传感器的上游附加一根炭管。将传感器的电阻临时采集到IC卡上。用fid -气相色谱仪（GC）每隔5min测量传感器附近排气的蒸气浓度，得到突破曲线。当相对湿度为0%时，所有被测有机气体（丙酮、甲乙基酮、乙酸甲酯、乙酸乙酯、甲醇、异丙酚、甲苯、1-丁醇、二氯甲烷、氯仿和1,1,1-三氯乙烷）的输出信号在识别突破之前就开始发生变化。当相对湿度为80%时，传感器也能检测到许多有机蒸汽在突破前被识别出来，但对二氯甲烷和氯仿不能检测到蒸汽的突破。在此基础上，开发了一种能够通知采样装置突破的报警系统。所开发的系统可以检测到许多有机蒸汽的突破，因此它将成为有用的炭管取样限制指标。

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.