Infrared gas analyzer

Claim 2

In apparatus capable of simultaneously measuring by energy absorption each of a plurality of components in a mixture of materials in a gaseous state despite any interfering energy absorbing characteristics of those components, the improvement which includes, in combination: voltage producing means for producing for each of said plurality of components a first voltage including a principal voltage and a first composite interference voltage; said voltage producing means comprising a plurality of optically aligned gas detectors, one for each component in the mixture to be measured; means for producing for each of said components said plurality of interference voltages each representing the interference of that component with a respective one of the other components to be measured; means for combining the interference voltages from each component related to a given other component to provide a second composite interference voltage corresponding to the magnitude of said first composite interference voltage for each component to be measured; and, cancelling means for combining said first and second composite interference voltages with opposing senses.

Claim 3

Apparatus according to claim 1 in which said means for producing a plurality of interference voltages includes potential dividers with adjustable taps.

Claim 4

Apparatus according to claim 1 in which said cancelling means includes a voltage adding circuit.

Claim 5

Apparatus according to claim 1 in which said voltage producing means includes phase shifting means.

Claim 6

Apparatus according to claim 1 in which said voltage producing means includes phase detecting means and phase shifting means coupled to said phase detecting means.

Claim 7

Apparatus according to claim 1 in which said voltage producing means produces direct current voltages.

Claim 8

Apparatus according to claim 1 in which said principal voltage, said first composite voltage and said second composite voltage are direct current to voltages.

Claim 9

Apparatus according to claim 1 in which said voltage producing means includes a filter, a rectifier coupled to said filter and a direct current amplifier coupled to said rectifier.

Claim 10

Apparatus according to claim 1 in which said voltage producing means includes a plurality of eneRgy sources each having an axis; a sample gas cell lying along an extension of the axis of one of said plurality of energy sources and adapted to receive a mixture of a plurality of gases; a reference gas cell lying along an extension of the axis of a second of said plurality of energy sources; said sample and reference gas cells having ends normal to said extensions of said axes and being transparent to the energy from said sources; said plurality of detectors each having first and second chambers, said first and second chambers having end closures transparent to said energy; said first chambers being in optical alignment with said first energy source; said second chambers being in optical alignment with said second energy source; each of said chambers containing a predetermined gaseous material; a flexible metallic diaphragm separating said first and second chambers in each of said detectors; said first chambers each including an electrode proximate to but spaced from and electrically insulated from said diaphragm in said detector; means interposed between said energy sources and said detectors for chopping the energy from each of said sources before it enters said detectors; and means coupled to each of said detectors for applying a potential between each of said electrodes and its associated diaphragm.

Claim 11

An infrared analyzer for measuring, simultaneously and accurately, the level of content of each of several principal gases in a mixture of gases, where such gases may have overlapping infrared energy absorption spectra and may be mixed with water vapor, which includes: a detector for each of the principal gases in said mixtures, each of said detectors producing an output voltage corresponding to the absorption of infrared energy at the primary absorption wavelength of a respective one of said principal gases; a detector for water vapor producing an output voltage corresponding to the absorption of infrared energy by water vapor; each of said detectors having coupled thereto its respective voltage divider with multiple, adjustable taps thereon; a plurality of summing amplifiers each having a principal voltage input terminal and at least one interference voltage input terminal, each of such plurality of summing amplifiers having its principal voltage input terminal coupled to a respective one of said principal gas detectors; said voltage divider coupled to said water vapor detector having said output taps on said voltage divider coupled to one of said interference voltage input terminals on each of said summing amplifiers; coupling means between each of said adjustable taps on each voltage divider coupled to a principal gas detector and an interference voltage input terminal on the summing amplifier coupled to each of the other principal gas detectors; a principal gas content indicator coupled to each summing amplifier; and said adjustable taps being positioned to assure readings on said gas content indicators which represent the respective gas content only.

Claim 12

An infrared analyzer for measuring, simultaneously and accurately, the level of content of each of several principal gases in a mixture of gases, where such gases may have overlapping infrared energy absorption spectra and may be mixed with water vapor, which includes: a detector for each of the principal gases in said mixtures, each of said detectors producing an output voltage corresponding to the absorption of infrared energy at the primary absorption wavelength of a respective one of said principal gases; a detector for water vapor producing an output voltage corresponding to the absorption of infrared energy by water vapor; each of said detectors having coupled thereto its respective voltage divider with multiple, adjustable taps thereon; a plurality of summing amplifiers each having a principal voltage input terminal and at least one interference voltage input terminal, each of such plurality of summing amplifiers having its principal voltage input terminal coupled to a respective one of said principal gas detectors; said voltage divider coupled to said water vapor detector having said output taps on said voltage divider coupled to one of said interference voltage input terminals on each of said summing amplifiers; coupling means between each of said adjustable taps on each voltage divider coupled to a principal gas detector and an interference voltage input terminal on the summing amplifier coupled to each of the other principal gas detectors; a principal gas content indicator coupled to each summing amplifier; and said adjustable taps being positioned to assure readings on said gas content indicators which represent the respective gas content only.

Claim 13

Apparatus according to claim 10 in which means are provided for adjusting the phases of the output voltages from each detector.

Claim 14

Apparatus according to claim 11 in which said phase adjusting means are mechanical.

Claim 15

Apparatus according to claim 11 in which said phase adjusting means are electrical.

Claim 16

Apparatus according to claim 10 in which the voltages applied to said principal voltage and interference voltage input terminals are a.c. voltages.

Claim 17

Apparatus according to claim 10 in which the voltages applied to said principal voltage and interference voltage input terminals are d. c. voltages.

Claim 18

Apparatus according to claim 10 in which said detectors for principal gases and water vapor include phase detectors.

Claim 19

Apparatus according to claim 10 in which said detectors for principal gases and water vapor each includes a filter, a rectifier coupled to said filter and a direct current amplifier coupled to said rectifier.

Claim 20

Apparatus accoRding to claim 10 in which said principal gases are CO, NO and HC.

Claim 21

Apparatus according to claim 10 in which said detectors include optically aligned chambers individually containing samples of the principal gases and water vapor.