Trace vapor detector

摘要

A detector for trace quantities of chemical species in the atmosphere includes a pump for drawing an atmospheric sample through transfer means which transfer species molecules present in the sample to a dry carrier gas circulating in a closed gas flow circuit including the transfer means, an ionmobility type detector, filters and a circulating pump; the filters remove water molecules and species molecules from the carrier gas. The carrier gas may be air. The arrangement inhibits water vapor reaching the detector and reducing its sensitivity to the chemical species.