Andros Incorporated

Andros Analyzers Incorporated

Andros Anlayzers Incorporated

New A.c., Inc. Dba Andros Incorporated

Kevin G Williams

Irvin G Burough

Robert E Passaro

George K Parnoff

Edward A McClatchie

Raymond E Rogers

Emery Major

William L Elder

Davood Khalili

Alexey Goder

Steven Drucker

Joseph John Kurtz

Kim S Christensen

Ken Christensen

An infrared gas analyzer includes an infrared source for emitting infrared energy, a sample cell for gases to be analyzed in the path of infrared energy emitted by the source and an assembly having first and second detectors also in the path of infrared energy and a third detector out of the path of infrared energy, mounted within the assembly and in close thermal proximity to each other and being responsive to impinging infrared energy to produce an electrical response. All detectors are sandwiched between a base and a single window that overlies them. The analyzer further includes a narrow band filter corresponding to an absorption wavelength band for a gas of interest and a narrow band reference filter corresponding to a reference wavelength band. Each of the narrow band filters are positioned outside the assembly and between the assembly and the source in the path of infrared energy.

Respiratory gas analyzer

Very generally, the gas analyzer of the invention includes a source of infrared energy, a sample cell for containing an analyte gas mixture positioned in the path of infrared energy, and a monochrometer including a movable diffraction grating for producing a beam of infrared energy wherein the constituent wavelengths are spetrally separated. The device also includes a wide band interference filter for transmitting a predetermined wavelength band spanning the characteristic absorption wavelength of each of a plurality of constituent gases in the analyte gas mixture. A detector positioned to receive radiation passing through the filter produces an electrical response related to the infrared energy impinging thereon. The monochrometer includes provision for moving the diffraction grating to sequentially cause infrared energy of different wavelengths to impinge upon the detector, and for intermittently causing infrared energy directed toward the detector from the source to be blocked by the interference filter.

Infrared spectrophotometer employing sweep diffraction grating

A non-dispersive infrared (NDIR) multi-gas analyzer has an optical element that is positioned with respect to the axis of incident IR radiation such that it passes nearly all of the IR energy within a narrow band pass to one detector and reflects nearly all of the IR energy outside the narrow band pass to another detector. Thus, the optical element simultaneously functions both as a narrow band pass filter and a beam splitter, which transmits nearly all the IR energy within a band pass and reflects nearly all the IR energy outside the band pass. Additionally, the separation of the incoming energy can be achieved without an extended roll off. This allows using a reference transmission band that is very close to the absorption band of the gases of interest. It more specifically allows using a reference transmission band that is located between the absorption bands for hydrocarbons and carbon dioxide in an infrared analyzer that uses beam splitters.

Multiple-gas NDIR analyzer

An improved apparatus and method for measuring the concentration of carbon dioxide in respiratory gases. The apparatus is a non-dispersive gas analyzer attached in series with the respiratory airway which is universally compatible with any host system. The analyzer includes a housing which supports a sample cell containing the respiratory gases, and which contains an infrared radiation source encased in shock absorbing material, means for directing the radiation into a collimated beam path through the sample cell, means for splitting the beam path and directing it towards a pair of infrared detectors for measuring the amount of absorption of carbon dioxide in the sample cell. The analyzer is further improved by the use of two heating servos, one for regulating the temperature of the sample cell windows in order to inhibit condensation build-up and one for regulating the ambient temperature surrounding the detectors so as to ensure more accurate measurements. Calibration means is included within the analyzer housing for storing and providing information characterizing performance parameters of the analyzer.

A non-dispersive infrared gas analyzer is disclosed that accurately measures the concentration levels of a plurality of gases within a gas mixture. The analyzer includes first and second sample cells and is utilized advantageously for the measurement of NO.sub.x and hydrocarbon gas present in the exhaust of an automobile engine. The gas mixture of the exhaust is chilled before entering the first sample cell to remove a substantial amount of the water vapor from that sample cell to facilitate measurement of the NO.sub.x gas. The second sample cell receives the gas mixtue in an unchilled state to allow for accurate measurement of the hydrocarbon gas. The analyzer includes processors which are utilized to further correct the NO.sub.x measurement and which also interact with each other to provide an output data stream that is representative of the concentration levels of the gases that are being analyzed.

Dual sample cell gas analyzer

A gas analyzer is described comprising a sample cell for containing a gas mixture to be analyzed, a source for producing and directing infrared energy through the sample cell, a rotary filter wheel having at least one filter thereon for passing infrared energy limited to a wavelength band within the characteristic absorption band of a predetermined gas and having a dark level region substantially opaque to infrared energy, a drive for supporting and rotating the filter wheel to successively interpose the filter and the dark level region between the source and the sample cell in the path of the infrared energy directed by the source, a detector for detecting infrared energy passing through the sample cell and producing an electrical signal representative thereof, and a signal processor connected to the detector for producing an output indicating the concentration of the predetermined gas in the sample cell by comparing the electrical signals produced by the detector with the filter positioned in the infrared energy path and with the dark level region positioned in the infrared energy path. The dark level region has a substantially fully reflective surface oriented toward the sample cell when positioned in the infrared energy path whereby infrared energy impinging thereon is reflected.

Digital anesthetic agent analyzer

Pulse modulated infrared energy is directed through a sample cell containing a gas mixture. The gas mixture may include a selected one of a plurality of gases. Each gas exhibits a characteristic absorption in the infrared wavelengths. A detector responsive to infrared energy at a preselected wavelength develops an AC signal having an amplitude proportional to the infrared energy passing through the sample cell at the preselected wavelength and having a frequency corresponding to the preselected pulse modulation frequency. The preselected wavelength is common to the absorption characteristic of each of said gases. The AC signal is processed to develop a DC signal having an amplitude determined from the AC signal. The DC signal is applied to an amplifier having a variable gain feedback which provides a plurality of gain steps. Each gain step is associated with a different one of the gases a single surrogate gas may be used to calibrate each gain step. The DC signal is amplified by the appropriate gain step to develop a second DC signal proportional to the concentration of the gas and the mixture contained in the sample cell. The amplifier may further include an analog to digital convertor which stores a digital equivalent of a zero offset output voltage of the amplifier when its input is grounded. The digital signal is reconverted to an analog signal and a current proportional to such signal is normally applied to the input of the amplifier to maintain zero stability.

Non-dispersive infrared gas analyzer

A non-dispersive infrared gas analyzer is described. Infrared energy is directed through a sample cell, and is interrupted at a predetermined frequency. The infrared energy at at least one preselected wavelength is detected to produce an AC signal having an amplitude proportional to the infrared energy passing through said sample cell and having a frequency corresponding to the predetermined frequency. The preselected wavelength corresponds to the characteristic absorption wavelength of a preselected gas. This AC signal is processed to produce a DC signal having an amplitude proportional to the concentration of the preselected gas in the mixture being analyzed. The signal processor includes an output amplifier, a voltage biasing network including a summing junction connected to the input of the amplifier, and a first variable control manually adjustable to bring the current at the summing junction to zero in the presence of a non-absorbing gas in the sample cell. A second variable control is connected in a feedback loop from the output of the amplifier to the input thereof for span calibration.

A gas analyzer of the non-dispersive infrared type is described. An infrared beam passing through a sample cell containing a gas mixture to be analyzed is detected. The resulting electrical signals are processed to produce an output indicating the concentration of the constituents of the gas mixture in the sample cell. The gas analyzer includes provision for temperature stabilizing both a rotary filter wheel and the detector, and for compensating the output of the signal processor for variation in the absorption characteristics of gas with temperature. The emissivity characteristic of the infrared energy source substantially compensates for wavelength dependence of the detector response. The motor drive for the rotary filter wheel is servo-controlled in accordance with synchronizing pulses developed directly from the detector output.

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Pinole, CA, United States of America

Kevin G Williams