A Computer-Controlled Continuous Air Drying and Flask Sampling System

A computer-controlled continuous air drying and flask sampling system has been developed and is discussed here. This system is set up for taking air samples automatically at remote places. Twenty glass flasks can be connected one by one or in pairs, and they can be filled at preset times, after preset intervals, or by online remote control. The system is capable of drying air continuously without operator intervention, with a flow rate of up to 4 L min^-1, to a dewpoint below -50°C. This enables continuous sampling, always retaining grab air samples of, for example, the last 24 h. This way, it is possible to decide afterward, according to online instrument records, if it is worthwhile to keep a single flask sample or even the whole diurnal cycle for later analysis at the laboratory. Dry sample air can be supplied to other analyzers. Four copies of the instrumentation are active at various places in Europe and have been shown to be able to run without servicing for periods of more than 1 month.