Method of compensating for carrier-gas-composition dependence due to the collision-broadening effect in non-dispersive infrared photometers having a detector comprised of two absorption chambers arranged one behind the other

摘要

The photometer comprises a light source, a reference cuvette containing a reference gas, a measurement cuvette containing a gas component whose concentration is to be measured accompanied by a carrier gas, a light modulator for effecting antiphase modulation of the infrared light passing through the two cuvettes, and a detector arrangement comprised of two gas-filled absorption chambers arranged one behind the other as well as a transducer for converting pressure changes induced in the absorption chambers into a measurement signal. The carrier gas consists of a plurality of component gases whose relative proportions fluctuate. The gas in the absorption chambers includes a gas component identical to the gas whose concentration is to be measured in the measurement cuvette, accompanied by an inert gas. The concentration of the infrared-active gas in the absorption chambers is repeatedly adjusted, until the measurement signal is made substantially independent of fluctuations in the relative proportions of the carrier-gas components.