| 摘要 |
The aim of the invention is to create a method and a device for detecting harmful substances while eliminating or minimizing the drawbacks of an ion mobility spectrometer (IMS). Said aim is achieved by a method in which the sample gas flow is mixed with a reference gas before reaching the detectors (2, 3, 4, 5, 6) and is directed to several detectors (3, 4, 5, 6) located next to the IMS (2), the obtained test signals regarding the ratio between the gas flow in the test gas path (8) prior to the metering process and the gas flow of the reference gas are used for calculating the original concentration of the harmful substances in the test gas, whereupon an alarm can be triggered by means of predefined and stored test values via a simple comparison of the signal amplitudes or a pattern recognition. The test system is cleaned and rinsed following the measurement phase by feeding the reference gas, if necessary also an additional cleansing gas. Such methods and test systems are used for identifying harmful substances in ambient air.
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