METHOD FOR MEASURING THE CONCENTRATION OF A GAS, AND DEVICE FOR CARRYING OUT THIS METHOD

摘要

A method for continuously measuring the concentration of a polyatomic, non elemental gas using an infrared irradiation photometer is described. An alternating radiation emitted by a pulsed radiation source (2) passes through an interference filter (3) and an absorption cell (4) and, optionally, a second interference filter (7) and strikes a radiation-sensitive receiver (8). The transmission range of the interference filters corresponds to the largest absorption maximum of the gas whose concentration is being measured. Flowing through the absorption cell is a gas mixture containing the gas whose concentration is being measured. After amplification, filtering and rectification, the output signal of the radiation-sensitive receiver is fed to one input of a summation circuit (13). A reference signal is fed to the other input of the summation circuit and is determined by feeding a gas free of the gas whose concentration is being measured through the absorption cell and zeroing with the aid of the indicating device for the concentration of the gas to be measured by appropriately altering the reference signal.