Infrared analyzer.

摘要

In an infrared analyzer of the disclosure a gas having no absorption at the characteristic absorption wavelength of a specified ingredient gas is introduced into a cell (1) to determine a zero gas measuring signal (VSO) and a zero gas comparative signal (VRO). A differential signal (VCO) obtained by amplifying a difference between said both signal and said zero gas measuring signal a memorized to subtract said differential signal (VCO) from a differential signal obtained by amplifying the difference between a comparative signal and a measuring signal when a sample gas is measured. The subtraction signal VC min received at this time is divided by said zero gas measuring signal (VSO), whereby a concentration of said specified ingredient gas is determined. According to the invention it is not necessary to introduce expensive span gas into the cell when conducting a span calibration so that not only the span calibration can be simple and inexpensively conducted but also the zero calibration and the span calibration can be carried out simultaneously and in a short time.