Acousto=optical gas measuring device - with pollutant enrichment cell preceding measuring chamber

摘要

In a device for measuring noxious substance concn. in a gas by directing intensity-modulated (esp. IR) radiation at a gas-filled opto-acoustic measuring chamber to induce gas pressure fluctuations, a gas enrichment cell (7) is provided having one or more enrichment surfaces (12, 13) in the beam path (5) between the radiation source (1) and the measuring chamber (14) for noxious substance molecule accumulation over a certain enrichment time. The noxious substance-loaded enrichment surfaces (12, 13) reduce the intensity of radiation incident on a reference gas in the measuring chamber (14) in accordance with the noxious substance concn. and the intensity redn. is evaluated by an evaluation circuit (17). Pref. the enrichment surfaces (12, 13) are formed of a polymer (e.g. polyethylene) capable of reversible accumulation of noxious substance molecules. ADVANTAGE - The device can detect low concns. of noxious substances, e.g. halogenated hydrocarbons, and has a simple construction. ( 1/1)