Gas analyser partic. for human breath - incorporates an in-situ system using carbon di:oxide snow for cleaning optical surfaces and thus allowing the analysis chamber to remain closed

摘要

Gas analyser comprising a chamber (10) with sample gas supply and discharge ducts (16, 20), optical elements (26, 28) which disperse light from an internal source, a detector (29) which analyses the diffusion of the light through the gas sample and a fixed spray system through which a sublimating material is directed onto the surfaces of the optical elements in order to clean them. Also claimed is the method of operation of the appts.