Abstract: A two-beam, infrared gas analyzer includes a front and a rear detection cell in each path filled with gas of the type to be detected; and a pressure-differential chamber with capacitor pick-up is connected to these front and rear cells. The rear cells are constructed to ensure substantially complete absorption of all radiation of the absorption band being characteristic of the component to be detected. In one example, filters are interposed between front and rear cells for broadband, i.e., nonselective attenuation. Alternatively, the rear cells are connected to a reservoir of the same gas to attenuate pressure variations. Either case enhances frequency selectivity by reducing cross sensitivity.

Abstract: An optical fluid analyzer uses the extent of optical, preferably infrared absorption of a fluid to be analyzed to determine the concentration of a selected constituant of the fluid. A first detector detects light after absorption by the fluid at a wavelength at which the selected constituant has a characteristic absorption for conversion into an electrical signal indicating the concentration of the selected constituant and a background from absorption of other constituants of the fluid for a measurement processing channel. A second detector correspondingly converts light after absorption by the fluid, but at a different wavelength at which the absorption at least approximates the background absorption alone for a neutral processing channel.

Abstract: In a bi-frequency infrared spectrometer having a filter wheel rotating in the path of rays, which filter wheel carries two semicircular filters transparent in different spectral ranges, the influence of the radiation from the filters themselves is eliminated in that the filter wheel has an opaque backplate on the side facing the light source, said backplate having one aperture in the area of each filter, which aperture passes through the path of rays. In this way the detector "sees", at first, only the filter with the radiation emanating from the filter itself, and is subsequently exposed to the measuring beam emanating from the light source and passing through the sample cell, when the aperture is being moved through the path of rays. A clamp circuit keeps the output signal zero until shortly before the aperture passes through the measuring beam. The detector signal is integrated by an integrator during a measuring time interval and a reference time interval.

Abstract: The invention relates to gas monitoring. Hitherto gas, such as flue gas has been analysed either by sampling and analysing the sample or by a spectrometer. However sampling is unreliable, and spectrography involves sensitive and expensive equipment needing extensive protection against vibration. In the invention, gas is monitored in situ by providing an infra red source and an infra red detector spaced across a gas flow, with a filter cell filled with the gas component to be monitored disposed between them. The detector detects radiation direct from the source and passing through the filter cell, and the outputs from the detector are fed to a differencing and dividing circuit to provide an output that is a function of the amount of monitored gas component in the gas flow.

Abstract: The cross sensitivity of a two-beam infrared gas analyzer is eliminated by using two differently long cells for the measuring gas in the two beam paths and by using an interference filter at least in the beam path containing the longer cell; the filter, however, does not filter the entire beam in that path.

Abstract: A system is described for precise monitoring and control of the carbon content of the atmosphere of a furnace such as a carburizer used in the heat-processing of steel parts. The disclosed apparatus includes a sampling system for withdrawing a gas sample from the atmosphere within a furnace and an analyzer for producing signals indicative of the partial pressures of at least two gaseous components such as carbon dioxide and carbon monoxide. The analyzer preferably utilizes selective absorption of narrow-band infrared radiation signals in determining these signals. A processor combines the signals indicative of partial pressures with parameters obtained from measurements of furnace temperature, and calculates carbon potential of the furnace atmosphere. The processor output is coupled with an atmosphere control which maintains desired levels of carbon potential in the atmosphere of the furnace by, for example, regulating the flow of an enriching gas to the furnace.

Abstract: The cross-sensitivity of a two-beam infrared gas analyzer is reduced by using two differently long cells for the sample gas in the two beam paths. The path with the short sample gas cell is intercepted by a detector cell having highly absorbing wall while the detector cell in the other path is highly reflective, e.g., made of gold. The two detector cells are interconnected by a differential pressure chamber with capacitive pickup.

Abstract: By autocorrelating the sample photoacoustic response signal and the reference photoacoustic response signal, respectively, obtained from the sample and reference cells, of a photoacoustic spectrometer, and cross-correlating the autocorrelated signals to produce a third signal, simple mathematical operations upon the resulting three signals will produce accurate sample analysis free from the effects of the noise arising from sample illumination intensity variations and other random phenomena.

Abstract: Infrared absorption gas analyzer systems are provided with cells containing sulfur hexafluoride SF.sub.6 for determining the water vapor content of the gas to be measured. In another embodiment, sulfur hexafluoride is used as a selective filter for removing spectral components from a beam of infrared energy so as to prevent cross sensitivity which interferes with the measurement of other gas components. Electrical signals proportional to the water vapor content may be produced by measuring the increase in gas pressure as infrared energy is absorbed, by use of a diaphragm capacitors. In another embodiment, temperature responsive resistors measure the relative attenuation of the infrared energy as it propagates through respective gas components.

Abstract: The present invention concerns a gas analyzer, for instance a CO.sub.2 analyzer, comprising a measuring chamber for the gas to be examined, a reference chamber from which the gas to be measured has been drawn off, a light source and a chopper disk, which chops the light beam to make it pass alternatingly through the measuring and reference chambers and so that in between there is a period during which no light is passed through at all, and an automatic gain control which maintains a constant difference between the "dark" signal and the signal delivered by the reference chamber. An attenuation member is positioned adjacent the reference chamber so the light beam passing through the reference chamber is attenuated to cause a shift of the operating point of the gain control circuit into the gently ascending part of the absorption versus concentration curve.

Abstract: An optical measurement system for eliminating the influences of time variations on light sources, transmission lines, photo detectors, etc. The system includes light sources which generate two pulse-shaped optical signals of different light wavelengths with a portion of the optical signals being transmitted to a measuring part in a distant place by a transmission line. In the measuring part, a change of a measured object is converted into a variation in the quantity of transmission of light, and the optical signal subjected to the variation is transmitted to a signal processing portion by a transmission line. The varied optical signal is converted into a first electric signal by a photo detector. Another portion of the optical signals from the light sources is converted into a second electric signal by another photo detector.

Abstract: A gas analyzer includes a first conduit for the supply of gas to be tested, a second conduit for the supply of a standard gas, first and second cells, a light source for directing light rays through the first and second cells, and a detector for receiving the light rays after passing through the cells. There is provided a gas flow change-over device connected to the first and second conduits for alternating at fixed intervals between a first gas supply arrangement wherein fixed amounts of gas to be tested and the standard gas are simultaneously supplied to the first and second cells, respectively, and a second gas supply arrangement wherein the fixed amounts of the gas to be tested and the standard gas are simultaneously supplied to the second and first cells, respectively.

Abstract: A gas analyzer for measuring the concentration of a gaseous component in a test gas includes first and second separate cells adapted to alternately be filled with a test gas containing a gaseous component to be analyzed and a standard gas, light sources for directing rays of energy through the first and second cells and through the test gas and standard gas alternately contained therein, a detector positioned to receive the rays of energy after passage thereof through the first and second cells for detecting the concentration of the gaseous component within the test gas, and a changeover device connected to the first and second cells and adapted to be connected to sources of the test gas and the standard gas for alternately supplying the test gas and standard gas, at fixed intervals and in fixed amounts, into the first and second cells.

Abstract: An apparatus for the quantitative estimation of the dispersion medium and one or more components forming the disperse phase of an emulsion or suspension or mixture thereof, wherein the mean particle size of the disperse phase is less than a selected absorption wavelength of the dispersion medium and also less than a selected absorption wavelength for each of one or more components of the disperse phase, and the said selected absorption wavelength of the dispersion medium is at a wavelength differing substantially from the or each selected absorption wavelength for the disperse phase component or components and the absorption by the or each disperse phase component is stronger than the absorption by the dispersion medium at the selected absorption wavelength for the or each disperse phase component.

Abstract: A method and apparatus for adjusting the gain of the sample and reference outputs of a chromatographic analyzer detector with respect to a reference voltage is provided. The detector sample output is compared to a voltage reference and this comparison is utilized to drive a dual color light-emitting diode. The light-emitting diode emits a first color when the gain is too high and emits a second color when the gain is too low. When the gain is correctly set so that the sample output is equal to the reference voltage when only carrier fluid is flowing through the sample side of the chromatographic analyzer detector, the light-emitting diode emits no light, thereby indicating that the gain is correctly set. A corresponding procedure is utilized to set the gain of the reference side of the chromatographic analyzer detector. The light-emitting diodes are also particularly useful as a diagnostic aid in optical absorbence chromatographic analyzer detector systems.

Abstract: Cylindrical method of quantifying fugitive emission rates from pollution sources, such as those emanating from ore mines, factories, office buildings, and the like.The method is characterized by its ability to quantify airborne fugitive emissions by defining an arcuate profile of pollutant flux, while driving a pollutant sensor in a peripheral arc surrounding the pollution source. According to wind changes, the pollutant sensor may be advanced peripherally of the pollution source to an arcuate detection plane downwind, so as to quantify fugitive emission rates, regardless of source emission characteristics or wind direction.

Abstract: A nondispersive gas analysis device with minimal cross-sensitivity to interfering gases includes cuvettes for a sample gas and a reference gas which are irradiated by modulated infrared energy. Radiation which has passed through the cuvettes passes unidirectionally and successively through receiving chambers which are dimensioned to be geometrically and optically alike. The chambers are coupled through conduits to a pressure responsive differential signal generator unit. Loss of radiation intensity due to the window between two sets of receiving chambers is compensated for by using suitable optical coatings on the receiving chamber windows or by forming the walls of the upper set of chambers from a material having a thermal conductivity differing from that of the material used in the lower set. An absorption chamber positioned after the receiving chambers has an IR absorbing disc with a plurality of concentric grooves formed to define a sawtooth pattern.

Abstract: The performance of a single light source parallel chambertype infrared gas analyzer is improved by enlarging the single inlet opening of the light divider and by positioning the light source such that the center axes of the two light passages of the light divider intersect at the light source. The assembly and alignment adjustment of the various functional components of the analyzer is also simplified.

Abstract: A body has two bores defining two cuvette chambers, one for holding a comparison gas and the other for holding a gas to be analyzed by comparison with the first. An infrared (IR) source at one end of the body provides in-phase radiation into the two cuvettes. At the other end is a window, a selective filter, a reception chamber for each cuvette, and an absorption chamber. The reception chambers are coupled to a device for producing a signal representing the difference in radiation reaching the reception chambers. The reception and absorption chambers are separated by a low reflectance window and the absorption chamber contains an IR absorbing body of glass, polymethacrylate or the like with concentric grooves.

Abstract: An illustrative embodiment shows infrared radiation divided into two beams which impinge on respective detectors via respective stationary filters, so as to provide measures of two constituents of a mixture of gases used for mixed anaesthesia. The same angled mirrors which provide the measurement beams may also be reflective on their sides toward the infrared source to provide reference beams to the filters and detectors such that the detectors may alternately sense the measurement and reference beams with the aid of beam interrupters.

Abstract: The sensitivity and selectivity of a two beam analyzer operating with negative filtering and differential absorption-pressure detection is improved by employing differently long cells for the sample gas in the two beam paths, which reduces the effect resulting from overlapping absorption bands of the wanted and of unwanted components in the sample gas.

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.

Abstract: Apparatus for determining the nitrogen oxide concentration in a gaseous mixture while minimizing measuring errors. The radiation from a hollow cathode lamp emitting the nitrogen oxide resonance radiation is modulated by a device for generating alternatively an unfiltered or test beam and a reference beam. The reference beam is filtered by a nitrogen oxide filled filter. An absorption cell is disposed in the path of the reference beam. Further, a monochromator or filter is provided and a detector for receiving the radiation from the monochromator filter. A signal processing unit is coupled to the detector for forming electric signals corresponding to the signal from the unfiltered and the reference beam and for forming the quotient thereof. A ray splitter is disposed in the path of the two beams to provide a different beam path and an additional radiation detector is disposed in the additional path.

Abstract: To detect the density of a measurement component of a sample gas, infrared light is directed alternately through a measuring-light optical system and a reference-light optical system to a heated light sensor. The measuring-light optical system includes a sample cell, a first filter for transmitting infrared rays of a fixed wave-length band, and a temperature compensating cell having a gas which has a part of its absorption wave-length band within the transmission wave-length band of the first filter but has a spectrum different from the spectrum of the measurement component. The reference-light optical system includes a light throttle, an interference cell having a gas containing a fixed density of the measurement component, an adjustable-length interference compensating cell filled with the sample gas, and a second filter for transmitting rays of a wave-length band that includes the major part of the transmission wave-length band of the first filter.

Abstract: A two beam radiation detector has two gas systems in a metal block. Each system has two detection chambers, one per incident radiation beam, and two chambers, pertaining to different systems, are traversed by the same beam. The two systems further include a common, but biparted, pressure difference sensing chamber containing a flexible membrane.

Abstract: Method of quantifying fugitive emission rates, such as those emanating from factories, office buildings, and the like. The method is characterized by its ability to quantify airborne fugitive emissions by defining a vertical profile of pollutant flux downwind of pollution sources. The method is thus a major improvement over conventional quasi-stack, roof monitor and upwind-downwind techniques of measuring pollutions. The method is characterized by its ability to quantify fugitive emission rates, regardless of source emission characteristics or topography.

Abstract: Presence of a substance in a gaseous medium is detected by introducing a sample of the gaseous medium under consideration into a variable volume cavity formed by the walls of a cylinder and the operating face of a piston reciprocable in the cylinder, the adiabatically compressing the gas in the cavity by cyclic reciprocation of the piston to increase the temperature of the gas and thereby cause emission of radiant energy by constituents of the gas sample at their respective characteristic emission spectra. The emissions are modulated in accordance with the recurrent variation of volume of the cavity. The piston is gas-centered during operation to inhibit sliding contact between surfaces and thereby permit oilless and powderless operation which would otherwise present contaminants tending to interfere with detection of the substances of interest.

Abstract: A spectrometer having two photoelectric channels the outputs of which are compared in order to measure gas or liquid concentrations, and means for automatically balancing the photoelectric channels immediately prior to each successive measurement, said means including a reference source of radiation which is utilized for balancing both photoelectric channels, so that when a measurement of the gas or liquid is being made, both photoelectric channels as nearly as possible are effectively balanced.

Abstract: Apparatus and process provide qualitative and quantitative analysis of sample constituent(s) in a stream of fluid, relatively free from qualitative ambiguities and quantitative zero displacements due to slowly changing contamination in the measurement stream. Slowly changing zero displacement of a continuous measurement signal -- caused by slowly changing contaminant concentrations in the stream -- is cancelled out by deriving two continuous versions of the measurement signal, both being time-distorted, and continuously manipulating the two versions as by subtraction.One of the two time-distorted versions serves as a primary or "main" signal; this main signal version is distorted in such a way that the time distortion of the other signal version is roughly symmetrical with respect to the main signal version, to improve measurement accuracy when the rate of zero displacement is nonlinear. In the case of spectral analysis, particular advantages lie in removal of misleading "background" spectral components.

Abstract: In a method for examining pulp for shives present therein a suspension of the pulp is passed through a measuring duct with transparent walls and two mutually perpendicular light beams are directed through the measuring duct in a plane perpendicular to the direction of flow in the measuring duct. The intensities of the light beams after their passage through the measuring duct are measured by means of two photo detectors and the output signals of the photo detectors are multiplied to provide a combined signal representing the product of the output signals of the photo detectors. This combined signal is analyzed with respect to the temporary amplitude reductions occurring therein due to the presence of shives in the pulp suspension flow passing through the measuring duct. Preferably, the light beams consist of light having a wavelength within the infra-red range.

Abstract: Method and apparatus for orienting and measuring fibrous particles by conducting longitudinally oriented fibrous particles through a beam of radiation and measuring the radiation scattered in a direction aligned with the length of such particle and, independently, also measuring the amount of radiation scattered transverse to the length of the particle. Preferably, the measurements are accomplished utilizing a sensor having an inactive center portion substantially corresponding to the area of undisturbed beam of radiation, a first photosensitive area in a portion of the sensor aligned with the length of the particles, and a second, independent photosensitive area transverse to the length of the particle. Signals generated by the two photosensitive areas are added to determine the size of the particles, and the ratio between the signals is established to determine the aspect ratio of the particle.

Abstract: Dual-beam comparison of gas absorption characteristics in which a single source and single detector of radiant energy and single chopper disc are used in sample gas and reference gas paths. Ambient atmosphere or gas directed through a sample gas chamber can be analyzed. Multiple gas analyses, of a plurality of gases or a plurality of constituents of a gas, can be performed simultaneously utilizing the single chopper disc with a plurality of optical gas assemblies. Each such assembly includes a single source of radiant energy, means for directing the radiant energy along sample and reference gas paths to a single detector for such radiant energy. The multiple units are mounted so that the single chopper disc cyclically interrupts radiant energy in the respective sample and reference gas paths in predetermined phase relationship. The combined sample gas and reference gas path response of the single detector for each gas analyzing unit is directed to phase-sensitive signal-separation circuit means.

Abstract: An infrared gas analyzer is provided with a first path for reference radiation and a second path for measuring radiation. A source emits infrared radiation into the first and second paths. A detector arrangement is positioned at the ends of the paths for sensing the intensity of reference and measuring radiation passing through the paths. A radiation-travel-control arrangement alternately blocks one and then the other of the two paths and during the blocking of each path causes radiation directed towards the blocked path to be deflected into the unblocked path so that such radiation is not wasted.

Abstract: A thermistor material is deposited and fired on a substrate, and an interdigitated pair of electrodes is deposited and fired thereover. The device is removed from the substrate and a third electrode of low thermal mass is applied on the side opposite the electrode pair. The three electrodes may be connected in a bridge circuit to form a novel, AC-generating infrared detector. When encapsulated in a header-type enclosure including a slit parallel to the electrode pair the sensor functions as an intrusion detector for moving objects. The thermistor material is preferably cobalt oxide.

Abstract: A dual path analyzer and a single path analyzer are disclosed, each for determining the concentration of one or more gaseous components in a mixture of gases. The preferred analyzer is a single path instrument which includes a source of infrared energy, a detector for the energy, a sample cell for the gas mixture positioned between the source and detector, and a filter wheel having a plurality of filters and a source blocking device positioned between the sample cell and detector for sequentially interposing the filters and the source blocking device between the source and the detector. Means are provided for amplifying the output signal of the detector and for processing the signal to provide a direct readout display which indicates the concentration of the gaseous components being analyzed.

Abstract: The contaminants in the exhaust gas emissions from a motor vehicle such as carbon monoxide (CO) and hydrocarbons (HC) are analyzed and the concentration of the contaminants together with other pertinent data is displayed in a digital manner. The exhaust gas emissions are fed into a sample cell contained within a nondispersive infrared analyzer and the absorption of an infrared radiation beam at selected wavelengths by the gas within the cell is measured. A reference cell containing a reference gas is also positioned in the infrared radiation beam path. By means of a rotating chopper disk positioned in the light path, the infrared radiation beam passes alternately through the reference cell and the sample cell and is focused at a plurality of detectors which are each sensitized to a narrow wave band by a filter and which receive the alternate sample cell and reference cell radiation pulses.

Abstract: A radiation receiver including three receiver layers for infrared gas analysis. The first and third layers are connected in parallel, and their pressure is compared with that of the second or middle layer to derive a pressure difference which compensates for certain measurement problems found in prior art devices.

Abstract: The contaminants in the exhaust gas emissions from a motor vehicle such as carbon monoxide (CO) and hydrocarbons (HC) are analyzed and the concentration of the contaminants together with other pertinent data is displayed in a digital manner. The exhaust gas emissions are fed into a sample cell contained within a nondispersive infrared analyzer and the absorption of an infrared radiation beam at selected wavelengths by the gas within the cell is measured. A reference cell containing a reference gas is also positioned in the infrared radiation beam path. By means of a rotating chopper disk positioned in the light path, the infrared radiation beam passes alternately through the reference cell and the sample cell and is focused at a plurality of detectors whch are each sensitized to a narrow wave band by a filter and which receive the alternate sample cell and reference cell radiation pulses.

Abstract: The contaminants in the exhaust gas emissions from a motor vehicle such as carbon monoxide (CO) and hydrocarbons (HC) are analyzed and the concentration of the contaminants together with other pertinent data is displayed in a digital manner. The exhaust gas emissions are fed into a sample cell contained within a nondispersive infrared analyzer and the absorption of an infrared radiation beam at selected wavelengths by the gas within the cell is measured. A reference cell containing a reference gas is also positioned in the infrared radiation beam path. By means of a rotating chopper disk positioned in the light path, the infrared radiation beam passes alternately through the reference cell and the sample cell and is focused at a plurality of detectors which are each sensitized to a narrow wave band by a filter and which receive the alternate sample cell and reference cell radiation pulses.

Abstract: A spectrophotometric method is disclosed for measuring the heating value of a mixture of substances commonly comprising a gaseous fuel. The method is based on the recognition that within certain wavebands the mixture exhibits a correlation between heating value and the strength of radiant energy absorption. A spectrophotometric apparatus is disclosed which is adapted to permit the continuous observation of the heating value of the mixture.

Abstract: The disclosure is directed to automatic flow blending of gas mixtures useful for calibrating gas analyzing instruments of the kind used in measuring atmospheric pollutants and the like. According to the disclosure the component gases reduced in pressure from the storage pressure, are continually mixed in a mixing zone at low pressure and pumped to high pressure for charging high pressure storage vessels. The mixture in the high pressure charging line is continuously monitored with a gas analyzer instrument. Variations from the desired blend are converted into an analog signal which is used to control various valve mechanisms for regulating the flow of gases to the low pressure mixing zone so that a match of the desired blend of gases is obtained.

Abstract: A method and arrangement for determining the concentration of nitric oxide n a gas mixture, particularly exhaust gases, wherein a beam from a hollow-cathode tube is directed through a modulator, an absorption cell containing a gas mixture with an unknown concentration of nitric oxide, and a monochromator, to a beam detector. A readout arrangement displaying the concentration of nitric oxide gas is operatively connected to the beam detector.