Process and assembly to measure the concentration of a gas e.g. carbon dioxide in a closed environment by comparison of infrared signals

摘要

In a process to determine the concentration of a gas, an infrared beam (08) is directed at a measuring sensor in a chamber. An identical beam is directed at a second sensor in a reference chamber, and the two signals are compared. The electrical voltage in the first infrared source is adjusted to equal that of the second and the change indicates the gas concentration. The measurement process is repeated at intervals as required. The infrared measurement detectors (100, 103) are a thermopiles. The first measurement is made in the measuring chamber and the second in the reference sensor chamber. The second value is recorded for subsequent repeat use. Also claimed is a commensurate assembly.