Infrared ray gas analyzing apparatus

Abstract

An infrared type gas analyzer having measuring and reference cells is equipped with alternately switchable valves so that the cells can alternate acting as the measuring and reference cells. The output of the detector is stored for each configuration and these outputs are subtracted from one another to provide the output of the analyzer.

What is claimed is: 
     
       1. An infrared ray gas analyzing apparatus of the type having a first cell irradiated by a first light beam of infrared rays, a second cell irradiated by a second light beam of infrared rays, a gas suppy means for supplying a sample gas to said first cell during a first period of time and a reference gas to said first cell during a second periof of time, a detector for receiving and comparing said first and second light beams passed through said first and second cells and providing an output signal, and a signal process circuit having a first output signal holding circuit for storing the output of said detector during said first period of time, a second output signal holding circuit for storing the output of said detector during said second period of time and a differential amplifier to which the outputs of said first and second signal holding circuits are applied, said amplifier providing the analyzer output signal, wherein the improvement comprises: said gas supply means supplying said reference gas to said second cell during said first period of time and supplying said sample gas to said second cell during said second period of time.   
     
     
       2. An infrared gas analyzing apparatus according to claim 1, wherein said gas supply means comprises: first and second gas inlet passages for providing gas to said first and second chambers, respectively;   first and second three-way valves each having one input and two outputs, each of said three-way valves having one output connected to each said inlet passage;   a reference gas source for supplying reference gas to the inlet of said first three-way valve;   a sample gas source for supplying sample gas to the inlet of said second three-way valve; and   valve control means for controlling said first and second three-way valves to thereby supply said reference and sample gases to opposite inlet passages during said first and second periods of time. .Iadd. 3. An analyzing-apparatus using infrared rays for measuring the density of an analysis gas in a sample gas comprising: a first cell irradiated by a first light beam of infrared rays; a second cell irradiated by a second light beam of infrared rays; means for receiving said first and second light beams passed through said first and second cells and providing an output signal in response thereto indicative of a density of the analysis gas contained in said sample gas being measured; and gas supply means for periodically supplying said sample gas containing said analysis gas to one of said first and second cells and a reference gas to the other of said first and second cells and, alternately, supplying said sample gas to said other of said first and second cells and said reference gas to said one of said first and second cells. .Iaddend..Iadd. 4. An infrared gas analyzing apparatus according to claim 3, wherein said gas supply means comprises: first and second gas inlet passage for providing gas to said first and second cells, respectively; first and second three-way valves each having one input and two outputs, each of said three-way valves having an output connected to each said inlet passage; a reference gas source for supplying reference gas to the input of said first three-way valve; a sample gas source for supplying sample gas to the input of said first three-way valve; and valve control means for controlling said first and second three-way valves to alternately supply said reference and sample gases to opposite inlet passages. .Iaddend.