Abstract: A respiratory gas monitor for measuring the concentration of certain gases in a respiratory gas stream has a compact and unitary lid assembly having an integral low-profile motor and a cylindrical infrared light beam chopper. The lid assembly also contains a motor position sensor and flex circuit for passing electrical signals through epoxy sealed orifices in the lid to a processing and control unit in the monitor. The flexible circuit uses releasable connectors to facilitate removal of the monitor from an external controller and the removal of the lid assembly from the bottom portion of the monitor.

Abstract: 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.

Abstract: Method of testing a property of a flowable substance. In particular this invention relates to the testing of the cross-linkability of an adhesive and is particularly relevant to an in-line process for mounting electronic components upon a printed circuit board. In the process, infrared light is passed through adhesive being fed to a dispensing position. Some of the light is absorbed by chemicals in the adhesive. Unabsorbed light after passing through the adhesive is analyzed and wavelengths of the light relating to cross-linkable materials in adhesive are monitored.

Abstract: A process for improving moisture analyzers or hygrometers that use optical absorption techniques to measure water vapor. Water vapor in the optical path outside the sample region is treated to exchange the hydrogen atoms for deuterium, so that the adsorbed water vapor is converted to heavy water, D.sub.2 O, and isotopically mixed HDO, thus reducing or eliminating the interference in any optical absorption apparatus for measuring water vapor, provided the spectral resolution is sufficient to resolve normal water absorptions from heavy water absorptions.

Abstract: Detection apparatus for use with a carbon dioxide jet spray cleaning system that determines whether liquid carbon dioxide is flowing between a storage tank and a jet spray nozzle. The detection apparatus determines whether carbon dioxide snow is generated by the jet spray nozzle, which is produced by expansion of liquid carbon dioxide through the jet spray nozzle. The apparatus comprises a transfer tube coupled between the storage tank and the jet spray nozzle that has transparent input and output windows and which permits liquid carbon dioxide to flow from the storage tank to the jet spray nozzle. A light source produces light that is focused on a pinhole in an aperture stop. A collimating lens images collimated light on the input window of the transfer tube, and a light detector detects light that is refracted by liquid carbon dioxide in the transfer tube that exits through the output window and is incident thereon, and generates an output signal indicating light detection.

Abstract: An infrared spectrometer for anesthetic gas monitoring using an infrared light source is divided into two separately sealed sections. A partition wall separating the two sections contains a partition window allowing infrared light to pass from the infrared source into a sealed sample chamber. In case of a failure of the sealed sample chamber the gas does not come into contact with the infrared source, thereby minmizing the risk of possible explosion. A gasket of neoprene or butyl rubber is used to seal the two sections from one another. The signal produced by the spectrometer indicating the composition of the sample gas is monitored to alert the user of a single point failure at the seal of the sample chamber.

Abstract: A transducer for nondispersive infrared radiation (NDIR) gas analysis and a passive device for verifying the calibration of the transducer. The calibration verification device can be mounted on a cable by which the transducer is attached to an associated signal processing-control-display unit (SPCDU) or monitor. Calibration parameters for the transducer are stored in a plug at the monitor end of the cable. The transducer includes an integrated subassembly of an infrared radiation source unit, an infrared radiation detector unit, and a flex connector and may be employed with an airway adapter preferably maintained by a thick film heating element at an above-dewpoint temperature to ascertain the concentration of a specie potentially present in gases flowing through the adapter. The transducer may also be employed for other purposes.

Abstract: Quantitative transmission spectroscopy where a sample liquid is applied onto a sample carrier having a net in such a manner that the liquid spreads across the meshes of the net. The liquid on the net is exposed to radiation essentially perpendicularly to the net, and the transmitted radiation is detected. The net accomplishes a dosing of the liquid in such a manner that identical meshes include identical quantities of liquid. For a given net, it is possible to derive the amount of liquid, which is located in a mesh and accessible to radiation, from a net constant. Knowing the amount of liquid detected by the radiation, it is possible to use the radiation absorption to calculate the concentration of one or several analytes contained in the sample liquid.

Abstract: A gas analyzer has a simple composition and can measure multi-components at a high accuracy. A plurality of measuring cells, including a case where the cells are different in length from each other, communicate sequentially with each other through a communication part to form a single gas path. A cut-on filter as an infrared penetration/reflection means for diffracting spectrally an infrared wavelength is provided on a light source side. A NO.sub.X measuring cell 3 having a cell length of about 60 mm and a CO.sub.2 measuring cell 7 having a cell length of about 1 mm which communicate through the communication part with each other, and a capacitor microphone (an infrared-ray detector for NO.sub.X) and a pyroelectric detector (an infrared-ray detector for CO.sub.2) are provided on the infrared penetration and reflection sides of the optical filter.

Abstract: The invention is directed to a measuring method for determining the concentration of a gas in a measurement sample with the aid of a combined measuring apparatus. The measuring apparatus includes a first infrared optical gas analyzer 1 as well as a second gas analyzer 2, which contains an electrochemical measuring cell 13. The measuring result of the electrochemical measuring cell 13 functions to correct the concentration, which is determined by the infrared optical gas analyzer 1, when the infrared optical reference measurement has already been performed on a measurement sample with this measuring sample not being free of the substance to be detected.

Abstract: A fire detector with a maximum average response time of less than 1.5 minutes is obtained by combining a smoke detector with a CO.sub.2 detector that uses NDIR sensor technology. The smoke detector is used to detect smoldering fires and to help prevent false alarms attributable to the CO.sub.2 detector. The CO.sub.2 detector is used to rapidly detect fires by measuring the rate of change of CO.sub.2 concentration. A signal processor generates an alarm signal when a smoldering fire is detected or alarm logic indicates that a fire has been detected.

Abstract: In a two-beam gas analyzer, a measurement beam passes through a measurement cuvette filled with a measurement gas, and a comparison beam passes through a comparison cuvette filled with a comparison gas. Using a detector arrangement, a difference signal is generated from the beams exiting from the two cuvettes resulting in a measurement value which corresponds to the measurement gas concentration when weighted with a weighting factor. To allow recalibration after a calibration of the two-beam gas analyzer with calibration gas and adjustment of the weighting factor to a value which results in the appropriate calibration value as the measurement value, without having to fill the measurement cuvette with a calibration gas, an additional factor is determined when the measurement cuvette is not filled or is filled with inert gas. Thus, the difference signal corresponds to the calibration value when weighted with the weighting factor and the additional factor.

Abstract: A photo-acoustic gas sensor for measuring a gas concentration, e.g., of an explosive gas, consists of a cylindrical sensor body (1) which includes a cylindrical measurement chamber (13) whose longitudinal axis extends perpendicular to the longitudinal axis of the cylindrical sensor body. Without changing the outer dimensions of the sensor body, the length of the measurement chamber can be changed in accordance with a desired measurement sensitivity and a desired measurement range. A light source (5) is disposed such that it irradiates the measurement chamber without irradiating a gas-permeable membrane (2), so that the membrane will not produce an interference signal. The gas sensor is rendered explosion-proof as the light source and a photo-diode (6) which monitors the light source are tightly sealed from the environment. Proper functioning of a microphone (4), the light source and the photo-diode are monitored by analyzing a background signal.

Abstract: A detector for an infrared gas analyzer is formed of first and second light receiving rooms filled with gas to be analyzed, a gas passage communicating between the first and second light receiving rooms, and a heat-sensitive resistance element disposed perpendicularly to the gas passage. The heat-sensitive resistance element includes at least one heat insulator having an opening at a center thereof, a pair of heat-wire elements disposed on the heat insulator to face against each other with a predetermined space therebetween, and a heating device. Each heat-wire element has a plurality of elongated elements disposed parallel to each other in the opening of the heat insulator, and connecting portions for connecting ends of the elongated elements for serially connecting the elongated elements. The heating device is formed on the heat insulator around the opening to equalize temperature in a space surrounded by the heat-wire elements in the opening. Accordingly, the analyzer can be operated stably.

Abstract: An air contamination monitor includes a sample heater connectable to an air source such as an aircraft engine bleed air port. The heater causes any oil and other hydrocarbons in the sample air to decompose into CO.sub.2 and H.sub.2 O. A vacuum pump draws the heated air sample from the heater to a carbon dioxide analyzer. The response of the analyzer is recorded by means of a strip chart or paperless recorder.

Abstract: An apparatus for measuring components in a liquid medium, in particular parenteral nutrients, with a flexible transparent bag. A spacer is utilized to fix or determine the optical path across the bag chamber and includes a passage for electromagnetic radiation of selected wavelengths. The source of electromagnetic radiation is capable of sending radiation into the bag chamber and to detector means which analyzes the radiation passed through or reflected from the components in the bag chamber.

Abstract: Contaminants are detected optically at concentrations below 1 part-per-million (ppm) and extending to a level approaching 1 part-per-trillion (ppt) by using intracavity laser spectroscopy (ILS) techniques. A diode laser-pumped solid-state laser (the ILS laser) is employed as a detector. The ILS laser comprises an ion-doped crystal medium contained in a laser cavity optically pumped by a diode laser pump laser. A gas sample containing gaseous contaminant species is placed inside the laser cavity and on one side of the ion-doped crystal. The output signal from the ILS laser is detected and analyzed to identify the gaseous species (via its spectral signature). The concentration of the gaseous species can be determined from the spectral signature as well. Advantageously, the diode laser pump laser is relatively small and compact in comparison to other sources of optical pumping.

Abstract: A miniaturized NDIR gas sensor is manufactured using semiconductor micromachining techniques from a semiconductor material such as Si or GaAs. The NDIR gas sensor comprises an optical waveguide, a light source at one end of the waveguide, at least one light detector at the end of the waveguide opposite the light source, a diffusion type gas sample chamber formed within the waveguide and interposed in the optical path between the light source and light detector so that the light source and light detector are thermally isolated from the gas sample, and a separate bandpass filter interposed between the light source and each light detector. A miniaturized NDIR gas sensor is also provided in which the light source and light detector are located on the same end of the optical waveguide is also provided. Because the NDIR sensor is fabricated out of a semiconductor material, the source driver and signal processing electronics may be added directly to the sensor using integrated circuit fabrication techniques.

Abstract: An apparatus for measuring isotopic ratios provides four separate optical paths for separate measurement of each of two isotopes relative to a reference signal, using spectrally resolved infrared radiation. The design permits the measurements to be made accurately without significant time lags between measurements, and without interchanging of cells or filters.

Abstract: Contaminants in corrosive gases are detected optically at concentrations below 1 part-per-million (ppm) and extending to a level below 1 part-per-billion (ppb) by using intracavity laser spectroscopy (ILS) techniques. A laser, the ILS laser, is employed as a detector. The ILS laser comprises a gain medium contained in a laser cavity. A gas sample containing gaseous contaminant species is contained within a gas sample cell which is placed inside the laser cavity and on one side of the gain medium. Accordingly, the corrosive gas is prevented from reacting with the components of the ILS laser. The output signal from the ILS laser is detected and analyzed to identify the gaseous species (via its spectral signature). The concentration of the gaseous species can be determined from the spectral signature as well.

Abstract: Gases can be selectively detected by utilization of an infrared (IR) absorption photometer via their specific absorption in the IR range. Known instruments are generally rather expensive, are of considerable size, require careful treatment and as a rule can be operated by skilled personnel only. The microstructured IR absorption photometer of the present invention is developed for (quasi-) continuously controlling a gaseous stream, the photometer being a single-piece shaped part manufactured as a microstructured body. The photometer is compact and robust, suitable for portable instruments and can be manufactured at low cost and in large numbers. The photometer can be made of metal and can be used even at an increased temperature. A flashlight lamp serves as an IR radiation source and a lead selenide receiver as an IR radiation receiver. The pulse repetition frequency of the flashlight lamp is from 0.01 Hz to 10 Hz. The pulse interval preferably amounts to more than a thousand times the pulse duration.

Abstract: The disclosed gas analyzer (10) provides two separate folded optical paths (16 and 18) from a single source (12) to a single detector array (14) via a polychromatic filter (26). One optical path (16) passes through a sample gas chamber (24) containing a gas to be analyzed and the other path (18) passes through a reference chamber (30) containing a reference gas. On each optical path (16 or 18), radiation from the source (12) is collected by upstream optics (22 or 28) to form a converging beam (16b, c or 18b, c), thereby reducing or eliminating the need for collection optics at the detector array (14).

Abstract: The gas sample identification apparatus transmits at least one beam of light of predefined frequency band through a gas sample present in a gas sampling chamber. The presence and concentration of various agents in the gas sample are determined by a linear variable filter that selectively passes the light beam transmitted through the gas sample chamber to an array of detectors. The detectors are positioned to receive only a narrow passband component of the light beam. The output signals from the array of detectors is processed by a multivariate statistical processor to accurately identify both the presence and concentration of one or more agents contained in the gas sample.

Abstract: Contaminants are detected optically at concentrations below 1 part-per-million (ppm) and extending to a level approaching 1 part-per-trillion (ppt) by using intracavity laser spectroscopy (ILS) techniques. An optically-pumped solid-state laser (the ILS laser) is employed as a detector. The ILS laser comprises an ion-doped crystal medium contained in a linear laser cavity which may be optically pumped by a diode laser pump laser. A gas sample containing gaseous contaminant species is placed inside the laser cavity and on one side of the ion-doped crystal. The output signal from the ILS laser is detected and analyzed to identify the gaseous species (via its spectral signature). The concentration of the gaseous species can be determined from the spectral signature as well. Advantageously, the linear cavity is relatively small and compact in comparison to other ILS systems.

Abstract: Multichannel infrared detector assemblies for use in the detection and monitoring of gas concentrations are provided.

Abstract: The source (12) has a heater element (122) sandwiched between elongate emitter plates (124 and 126). In operation, the source (12) is operated at temperatures in excess of 900.degree. C. and, preferably, at least about 1200.degree. C. to provide radiation in the 7-10 micrometer wavelength range. In one embodiment, the source (12) is used in conjunction with an elongate detector array (14) in a gas analyzer (10) for analyzing respiratory and anesthetic gases. Spherical mirrors (36a, 36b) and flat mirrors (38a, 38b) are employed to image the source (12) on the detector array (14). A linear variable filter (26) allows for analysis of the radiation at multiple wavelengths using detector array (14).

Abstract: In addition to analysis in the infrared spectra of hydrocarbon group types, it has now been found that certain hydrocarbon species, including preferably aromatic species such as benzene, toluene, xylene, and alkyl benzenes such as ethyl benzene, can be determined by measuring absorption in certain selected wavelengths in the infrared spectra, then manipulating the data, e.g., preferably by taking the first or higher derivative, and applying statistical techniques, preferably multiple linear regression (MLR) to provide an output signal indicative of the concentration of the particular specie. The output signal can be used to control refinery and chemical processes, e.g., reforming, catalytic cracking, alkylation and isomerization. In manufacturing reformulated fuels, government regulations can be complied with by utilizing the invention to blend fuels which have a maximum of benzene or other regulated components.

Abstract: The invention includes an on-board diagnostic system for monitoring exhaust gas from an automotive combustion engine and includes a sample port connected to the exhaust piping, preferably downstream from the catalytic converter. The exhaust port leads to a sample cell to which an infrared spectrometry system is operably connected to measure the concentration of hydrocarbons in the sample cell. An air pump is connected to the exhaust port and communicates with the sample cell. The air pump is operated to continuously purge the sample cell by pushing small amounts of clean air through the sample cell into the exhaust.

Abstract: The invention relates to a process for analyzing traces of at least one impurity in a gas sample, by absorption by the impurity to be detected of a light beam emitted by a semiconductor diode laser, the beam emitted by the diode being split into at least two branched beams, one called the measurement beam which passes through the gas sample to be analyzed in a multipassage cell before being focused onto a measurement photodetector, another branched beam, called the reference beam, being along a reference path and directly focused onto a reference photodetector without encountering the gas sample, in which process the gas sample is at a pressure at least equal to atmospheric pressure, and a modulation of the supply current of the diode has been introduced, which comprises at least one function of the exponential type.

Abstract: A measuring apparatus for measuring the concentration of a gas by infrared absorption includes a first radiation source 11 having a first modulation frequency, an arcuate waveguide 13 for receiving the gas to be measured therein, and two radiation detectors (15, 16). The measuring apparatus of the invention is a compact gas measuring apparatus having a simple configuration. The temperature dependent and deterioration dependent changes of the two radiation detectors (15, 16) are compensated. A second radiation source 12 having a second modulation frequency is mounted between the first radiation source 11 and the radiation detectors (15, 16).

Abstract: An ultraviolet light source is provided on one end of a cell into which a sample gas is introduced. A beam splitter for dividing beams which have been transmitted through the cell into two optical paths is provided on the other end of the cell. A first detector is provided in one optical path, and a second detector is provided in the other optical path. A gas filter filled with a component to be measured is positioned between the detectors and beam splitter so that a concentration of the component to be measured may be obtained on the basis of a difference between the output of the first detector and the product of the output of the second detector and an appointed constant. Influences resulting from components coexisting in the sample gas are reduced. Alternatively, an infrared light source may be provided on one end of a sample cell. A gas filter filled with a gas the same as the gas to be measured is provided at the other end of the sample cell.

Abstract: Gas analyzer systems which include: (1) a transducer for outputting a signal indicative of the concentration of a specified gas in a sample which may contain that gas, and (2) an airway adapter or cuvette with a flow passage for confining the sample to a particular path traversing the transducer. The cuvettes feature radiant energy transmitting windows which are flush mounted in apertures on opposite sides of the cuvette flow passage and are fabricated from a polymer such as biaxially oriented polypropylene which is malleable, yet resistant to wrinkling, warping, and other forms of distortion. Retainer rings keep the windows flat and distortion free with an accurately reproducible spacing between the windows.

Abstract: A gas analyzing apparatus comprises a light source (34) emitting an infrared luminous flux; a sample cell (38) which is arranged such that a sample gas is introduced therein and the infrared luminous flux emitted from the light source (34) is transmitted therethrough; and detection means (10a, 10b) which contain absorbers and are arranged such that the infrared luminous flux transmitted through the sample cell (38) passes through the absorbers and an increase in pressure according to the temperature within each of their absorber containers raised upon absorption of the infrared luminous flux by each absorber is optically detected so as to measure, based on the increases in pressure, concentrations of ingredients to be measured in the sample gas, wherein, as the absorbers contained in the detection means (10a, 10b), gases having ingredients identical to the ingredients to be measured are used, respectively.

Abstract: A method and apparatus serve to determine spectroscopically a concentration of ethanol in a test sample of an alcoholic aqueous beverage. The determination is based upon providing calibration data which establish a relation between(A) a plurality of transmission values of an electromagnetic radiation in the near infrared region, measured at a unique wavelength at which water is relatively opaque to the radiation while ethanol is relatively transparent thereto, of a plurality of calibration samples of the beverage containing ethanol in differing known concentrations, and(B) the known concentrations of ethanol in the calibration samples. Then, at least one light transmission value of the test sample at the unique wavelength, at which said calibration data were established, is measured. The measured transmission value of the test sample is transformed, by way of the relation established by the calibration data, into an indication of the concentration of ethanol in the test sample.

Abstract: A device and a related method of operation of the device for continuously monitoring the progress of a steeping beverage during the steeping process is disclosed which provides an indication to the user when the steeping beverage has reached an adjustable, desired level of steeping to thereby enable the making of a consistently steeped beverage without requiring the steeping operation to be timed or otherwise closely monitored. The device optically monitors the steeping beverage by using a photo diode to detect light from an LED which passes through a fixed measurement aperture immersed in the steeping beverage. By determining when the passage of light through the measurement aperture has decreased to a predetermined level indicative of both the color and the strength of the steeping beverage, an alarm may be provided to indicate that the beverage has steeped to precisely the strength desired.

Abstract: An improved method and apparatus for use in optical testing of concentration in samples has been developed. The apparatus restricts the solid angle of illumination and the solid angle of detection to eliminate a high proportion of the scattered radiation while allowing the ballistic radiation and the snake-like radiation to be transmitted. In samples which contain multiple scattering centers, this allows less correction for variations in effective pathlength and allows easier calibration of the apparatus. The use of polarized radiation as a means of minimizing scattered radiation in the sample is also disclosed.

Abstract: In a method and an apparatus for determining a content of an aliphatic hydrocarbon insoluble matter in a residual fuel oil, the method includes the steps of: (a) measuring absorbances of a sample solution having an aliphatic hydrocarbon insoluble matter suspended in the sample solution at two spaced wavelengths of light in a wavelength range from 500 nm to 1,000 nm; and (b) performing an operation to determine the content of the aliphatic hydrocarbon insoluble matter in the sample solution by inserting the measured absorbances into the specific correlations. The contents of the insoluble matter in aliphatic hydrocarbons and asphaltene in the residual fuel oil can be determined in a precise and rapid manner even if the oil contains the particles of aromatic hydrocarbons such as toluene.

Abstract: An oil concentration meter includes a sample cell for receiving an oil sample that can be irradiated with infrared rays from a light source. A first interference filter having a design wavelength of 3.4 .mu.m is positioned before a measuring detector, while a second interference filter transmitting a band range between 1 .mu.m and 5 .mu.m is positioned in front of a reference detector. A logarithm of the ratio of the reference detector output to the measuring detector output is used for determining the oil concentration in a sample.

Abstract: A radiation source assembly for optical transducers used for the analysis of material components of media, whereby the radiation source assembly comprises: two thermal radiation sources (1, 2), of which the first radiation source (1) is located, in relation to the second radiation source, in such a position that it emits through the second radiation source (2); a band-stop filter (10) located between the first and the second radiation sources, so that the radiation (6) emitted by the first radiation source passes through it. Both thermal radiation sources (1, 2) comprise a substrate (3, 11) made of silicon, of a silicon mixture or of a silicon compound, and a recess (53) made in the substrate, and micro-filaments (4, 5), which are fastened at their ends to the outer surface (51, 52) of the substrate, their radiation (6, 8) emitting regions being at a distance (H) from the bottom surface (54) of the recess.

Abstract: A diode laser spectrometer includes a sample chamber for holding a sample gas, e.g., human breath, having first and second isotopic species in an unknown concentration ratio and a reference chamber for holding a reference gas having the first and second isotopic species in a known concentration ratio. Laser light is directed through both chambers at wavelengths corresponding to absorption wavelength of the isotopic species, and the light is detected and sample and reference signals generated. The signals are processed by a computer to determine the concentration ratio of the first isotopic species to the second isotopic species in the sample gas. The diode laser is cooled by a thermoelectric cooler or a cryocooler operating as a reverse Sterling engine.

Abstract: A method and apparatus for conducting laser absorption spectroscopy uses a frequency tunable laser aligned to pass a laser beam through a sample volume and to an optical detector. A two-step modulation is used to generate frequency components that may be used to both lock the tunable laser to the absorbance signal, and generate an output signal proportional to the absorbance signal. The method includes frequency modulating the tunable laser at a first frequency while further modulating the tunable laser with a triangular waveform having a second frequency, and generating a feedback control signal based upon an antisymmetrical signal demodulated from the optical detector using a first predetermined harmonic of the second frequency. The tunable laser is locked to the absorbance signal with the feedback control signal. An output signal proportional to the absorbance signal is generated using a symmetrical signal demodulated using a second predetermined harmonic of the second or triangular waveform frequency.

Abstract: The absorption of laser radiation by a gas (such as oxygen and/or carbon dioxide) in human breath is detected on-airway by generating laser radiation using a laser diode, passing the laser radiation through a volume containing human breath multiple times, and detecting the laser radiation which is not absorbed by gases in the volume. To reduce the amount of energy required to control the laser diode, a laser diode is selected which generates laser radiation having a wavelength which is reasonably close to the wavelength of an absorption line of a desired gas when the laser diode is at or near normal body temperature. By passing the laser radiation through the sample gas multiple times, a longer path through the sample gas is provided for absorption thereby allowing the concentration of a gas having weak absorption lines (such as oxygen) to be determined using on-airway absorption detection.

Abstract: A stack gas monitor system has an optimized gas flow portion which is permanently installed in a fossil fuel burning facility, and to which a spectrophotometric portion can be readily coupled for real-time determination in the system of a concentration of a first gas having a characteristic absorption spectrum and which is selectably introducible as a measured amount into a stack gas stream. A sample of the stack gas stream is flowing through the gas flow portion, with at least one gas of the sample stream having an absorption spectrum extending within an ultraviolet range of wavelengths of radiation and having absorbance values within this range which are higher than absorbance values of the first gas. The system can be purged and can be calibrated with the first gas. Stack gas blank data are obtained in the absence of the first gas. Composite gas data are provided upon introduction of the first gas into the stack gas.

Abstract: Apparatus and method are provided for testing of exhaust gas emissions from an internal combustion engine, and determining the engine's operating condition. An inferred value for the ratio of hydrogen to carbon in the exhaust, based on measured values for the H.sub.2 O, CO.sub.2 and CO components of the exhaust gas, is used to determine whether the engine and associated exhaust componentry have reached normal operating conditions. The emissions testing apparatus and method are suitable for remote testing of exhaust gas emissions from an internal combustion engine of an on-road motor vehicle. A light source emits preferably near to mid-infrared light to impinge upon the exhaust gas emissions. The emitted light includes wavelengths absorbed by exhaust species to be measured, including at least H.sub.2 O, CO.sub.2 and CO. Following impingement on the exhaust gas emissions, the light is received by a sensor which generates an output signal corresponding to the amount of light received at each of such wavelengths.

Abstract: A photoacoustic device for analysis of fluids. The device is made up of (A) a source of a pulsating beam of light, preferably of the chopper type, and (B) an enclosure, preferably an elongated structure having a generally cylindrical, e.g. essentially tubular shape; and containing and holding--in sonic insulation--at least one reference chamber and at least one measuring chamber in an essentially linear or serial arrangement in a common cell within the enclosure, preferably in an essentially coaxial arrangement; the enclosure and the common cell provide a path P for the pulsating beam of light through the reference chamber and through the measuring chamber. For most purposes, it is preferred that the light beam pass first through the reference chamber and subsequently into the measuring chamber. Optionally, a second reference chamber is arranged at the end of the measuring chamber and a second measuring chamber may follow.

Abstract: Gas analyzer systems which include: (1) a transducer for outputting a signal indicative of the concentration of a specified gas in a sample which may contain that gas, and (2) an airway adapter or cuvette with a flow passage for confining the sample to a particular path traversing the transducer. The cuvettes feature radiant energy transmitting windows which are flush mounted in apertures on opposite sides of the cuvette flow passage and are fabricated from a polymer such as biaxially oriented polypropylene which is malleable, yet resistant to wrinkling, warping, and other forms of distortion. Retainer rings keep the windows flat and distortion free with an accurately reproducible spacing between the windows.

Abstract: A method and apparatus for the rapid estimation of the gas concentration within the headspace of a production beverage container which contains a carbonated beverage, includes preparing a prediction model based on correlations between an infrared absorption spectrum obtained from an analysis container and corresponding measured values of gas concentrations and physical properties of the analysis container, the method, whereby the physical property or gas concentration within the headspace of production container do not need to be measured directly, but rather are estimated based on the prediction model with a measured infrared absorption spectrum as an input to the prediction model, thereby providing non-invasive monitoring of production containers, filled and pressurized.

Abstract: Apparatus and method of monitoring fluid presence, wherein electomagnetic radiation sources (1, 2) provide respective reference and sample beams (12, 22), the wavelength of the radiation preferably being matched with that of the absorption spectrum of a fluid to be monitored. A first reference cell (13), containing a reference sample of the fluid to be monitored, has the reference beam (12) passed through it, whilst a second, sample cell (33) containing any working sample of the fluid to be monitored, has both the reference and sample beams (12, 22) passed through it. Subsequently, the reference and sample beams are detected independently of each other to provide respective signals representative thereof, which signals are then compared to determine the presence, and preferably also the concentration, of any sample fluid in the second cell.

Abstract: A system and method for determining the presence of multiple vapor gases in a refrigerant sample. An infrared light source illuminates a refrigerant sample located in a test area between the light source and a plurality of infrared detectors. Each of the infrared detectors is sensitive to a different predetermined wavelength range of infrared light, with each of the detectors outputting a separate electrical signal corresponding to the infrared light received in its respective wavelength range. A processor then reads the output electrical signals and determines whether the electrical output signals correspond to a particular refrigerant and displays the result of the determination on a display.

Abstract: A method for calibrating a gas analyzer (1). A gas analyzer is calibrated by measuring the zero level of the analyzer (1). The level of the analyzer is measured, after a preceding reset, whenever a temperature variation (.DELTA.T) of an infrared sensor (14) included in the analyzer (1) or of a component thermally connected in a highly conductive manner thereto exceeds a predetermined threshold value (A), or the temperature variation rate (D) of the infrared sensor (14) of the analyzer (1) or of a component thermally connected in a highly conductive manner thereto exceeds a predetermined limit valve.