| Summary: | 碩士 === 中國文化大學 === 勞工研究所 === 89 === The study was tried to investigate the influence of charcoal tube’s orientation on the sampling efficiency. When toluene was use as target compound for sampling, the test was conducted under different effects of concentration, flow-rate, temperature and relative humidity. Among twelve samplings tested, most of the sampling with activated charcoal tube were at the vertical orientation with the breakthrough time being the longest when the air went through the tube from bottom to the top. If the tube was at the vertical orientation and the air went through the tube from top to the bottom , the breakthrough time was shortest. While the tube was at the horizontal orientation, the breakthrough time was in between. There were exceptions to a few cases（there sets）. The reason for this phenomenon was thought to be when air came from bottom to the top of the sampling tube, the air and gravity were at the opposite directions. This gradually caused the particles of the sampling medium to vibrate. Especially when the packing of the sampling tube was loose at the beginning, this phenomenon was more obviously. Due to the spaces between the particles were increased, the sampling tube has higher surface area. Therefore, the capacity of the adsorption was increased and increased the breakthrough time was increased too.
The study did not investigate the factors of mediums and the hydrophilicities of the substances. Therefore, we could make the same conclusion for every sampling case.
Since the results of this study indicate the orientation of the sampling tube has an influence on the breakthrough volume, it is suggest that when evaluating or working out sampling methods, one should consider this factor and offer indication in order to avoid bias caused by this factor.
Key words：charcoal tube, orientation, breakthrough
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