Infrared gas analyser - using tiltable filters before gas-filled receivers for better selectivity

摘要

An infrared gas analyser, with two parallel paths for the rays, one through a measuring chamber and the other through a reference chamber, has two gas-filled receiver chambers feeding a diaphragm capacitor to measure the pressure differential. The receivers are preceded by tiltable filters, which reduce the radiation in the overlapping absorption band of the component to be measured and any disturbing component. The distance of the filters from the receivers is adjustable. Used for measuring NO-content in the exhaust gases of motor cars. This improves the selectivity of the analyser in the presence of disturbing gas components, i.e. the lateral sensitivity caused by the disturbance is reduced.