Abstract: Apparatus and methods are described for determining particulate concentrations in an exhaust gas. One embodiment provides a method of analyzing particles in a gas using an apparatus including a probe and an analyzer. The method includes obtaining a sample of particle laden gas through the probe; obtaining ambient air through the probe; diluting the sample with the ambient air; and providing the diluted sample to the analyzer. Another embodiment provides an apparatus for analyzing particles in a gas. The apparatus includes a probe adapted to accept a gas or ambient air; a volume to dilute the gas with the ambient air; an analyzer responsive to particles in the gas; and electronics to operate the apparatus. The electronics instructs a user to first provide a sample and then provide ambient air into the volume, and then analyzes substantially all of the sample and ambient air for particles.

Abstract: This invention relates to a suction-type smoke sensing system which detects smoke with high accuracy and rapidly and identifies a fire occurrence spot quickly. The system of the present invention is provided with a piping for sucking air in each region to be inspected, a photoelectric smoke sensor which, when air in each of the regions to be inspected is sucked, senses mixing of smoke in the air, and a control unit which sucks the air in the region to be inspected and is electrically connected to the photoelectric smoke sensor so as to receive and process a detection signal.

Abstract: The invention provides use of one or more emitted beams of radiation (16), for example, laser beam(s), in combination with an image capturing means (14), for example, one or more video cameras and/or optical elements to detect particles (30), for example smoke particles, located in an open space (12).

Abstract: A laser gas analyzer which can include a light source unit including a diode laser that irradiates a gas to be measured with laser light while scanning a wavelength thereof; a detection unit including a light receiving element, a gain-variable amplifier into which an output signal of the light receiving element is input, an A/D converter into which the output signal of the amplifier is input, and an arithmetic processing unit that performs a concentration analysis of the gas to be measured; a peak-to-peak detector that detects a peak-to-peak value of the output data of the A/D converter in each scan of the wavelength of the laser light irradiated from the diode laser; and a gain adjustment unit that, when the output signal of the peak-to-peak detector deviates from a preset threshold, adjusts the gain of the amplifier in a direction of bringing the output signal back to within the threshold.

Abstract: Method and device for quantifying ingredients of a plume. In one embodiment, the method includes sweepingly directing a beam of light through the plume to a surface on which the beam of light is scattered, acquiring the scattered light scattered from the surface, and processing the acquired scattered light to determine an amount of ingredients of the plume. In one embodiment, the height of the back of the vehicle is measured as the top of the plume for calculating the total mass-per-distance of the plume. In another embodiment, by comparing the absorption spectrum of the plume and the background absorption spectrum of which no plume exists, the non-methane hydrocarbons (NMHC) of the plume emitted from a vehicle can be quantified.

Abstract: A soot number determining device has an intake line for taking in a soot-containing gas through a filter paper that has been introduced into the intake line. A transport apparatus transports a soot spot, which is produced at an intake position by virtue of the gas being taken in on the filter paper, by transporting the filter paper further to an evaluation position. A device is used to determine the extent of blackening of the filter paper.

Abstract: A photoacoustic detector for providing a measurement, includes a first light source and a second light source each configured to provide light of a same intensity while retaining a same spectral distribution. Additionally, the photoacoustic detector includes a first beam path allocated to the first light source and at least one second beam path allocated to the second light source, wherein a different absorption of light occurs in the first path and the second beam path in at least one selected wavelength range. Further, the photoacoustic detector includes a photoacoustic measuring cell; and a mechanism for alternately guiding light from the first beam path and from the second beam path into the photoacoustic measuring cell.

Abstract: A system for detecting engine fluid constituents includes an engine having a sample channel having a conduit for a working engine fluid. The system includes an electromagnetic (EM) source that emits EM radiation through a first metal tube, where the EM radiation is EM energy at a wavelength of interest. The system further includes an EM detector that receives a remainder radiation through a second metal tube, the remainder radiation including the remaining EM radiation after passing through the sample channel. The system includes a controller that determines a composition indicator signal representative of an amount of a constituent in the working engine fluid in response to a strength of the remainder radiation, and determines a concentration of a component of interest according to the composition indicator signal.

Abstract: In one aspect, the present invention relates to a device quantifying absolute amounts of ingredients of a plume. In one embodiment, the device comprises a source for emitting a beam of light and transmitting the emitted light through the plume to a surface on which the transmitted light is scattered, a detector for acquiring an image of the exhaust plume, the acquired image containing information of absorption of the scattered light scattered from the surface, and a processor for processing the acquired image to determine an absolute amount of at least one of components of the exhaust plume.

Abstract: A smoke detector has a housing, a smoke sensor in the housing capable of detecting smoke therein, and an alarm connected to the sensor signaling when the smoke sensor detects smoke. A partition subdivides the housing into separate first and second chambers, and the housing is formed with first and second smoke holes allowing air from the exterior into the first and second chambers. The partition has a sensor port provided with a sensor for detecting air flow through the sensor port and a fan port having a fan for drawing air from one of the chambers and forcing it into the other chamber. A controller connected to the fan and to the air-flow sensor operates the fan means to move air from the one chamber through the fan port into the other chamber and generates an output when air flow through the sensor port exceeds a predetermined limit.

Abstract: A method of mapping concentrations of airborne matter from an emission source of interest in an emission plume is provided. The method involves measuring airborne matter at one or more than one identified locations using an optical sensing instrument (OSI) operatively connected with one or more than one matter samplers and mounted on a vehicle. The one or more than one airborne matter samplers are passed through an airspace to be sampled, and one or more concentration measurements are obtained. Geographic positions and altitude values for each of the one or more identified locations are established, and a point concentration measurement for the airborne matter for each identified location determined. The concentration measurements are mapped relative to the geographic position and altitude values for each of the one or more identified locations to obtain an airborne matter concentration distribution map in one or more measurement surfaces through a cross-section or profile of the emission plume.

Abstract: A system for analyzing smoke has a plurality of units, wherein each unit includes an optical emitter for alternately directing horizontally and vertically polarized light along a beam path, and into a smoke cloud, to generate scattered light. A horizontally polarized detector and a vertically polarized detector are positioned at different locations, but at a same distance and scattering angle relative to the beam path. Each unit has a different wavelength. A computer receives signals from the detectors of all units, in response to each emitter, for analysis of the smoke.

Abstract: A method and device for measuring trace levels of particles in an air sample is described. A device operating in a gradiometer configuration with two cavities built from a monolithic structure and utilizing a single probe laser, provides common mode subtraction of acoustic, vibrational, laser intensity and other noise sources, which allows sensitivity more closely approaching the quantum limit. Differential measurements between the two cavities occur simultaneously, which reduces errors due to cavity drift. Absorptive gradiometry can therefore provide noise immune detection for trace gasses, including broad linewidth absorbers where frequency-noise immune schemes are not practical. Differential measurements can be used for background subtraction, sensing vapor plum gradients and determining vapor plume propagation direction.

Abstract: Provided are sensors and methods of measuring the oxygen concentration of a fluid. An excitation light source is in optical communication with a transducer for transmitting an excitation light that is at least partially absorbed by the transducer. The transducer has a property of photoluminescence, and enters a higher energy state by at least partially absorbing the excitation light and enters a lower energy state through radiation of emitted light, thus producing spectral indicia. A light detection system, which is also in optical communication with the transducer, processes the spectral indicia to determine the concentration of oxygen in the fluid.

Abstract: A diesel particulate matter (DPM) monitor that can be worn, attached to a particular location or piece of equipment, and collects real-time data about DPM levels. In an exemplary embodiment, ambient air is drawn by a flow-controlled diaphragm pump through a particle size selector which only passes submicron particles. These particles are collected on an optically transparent filter. A laser illuminates the filter and the transmittance of the laser beam is measured in real-time by a photo detector. As DPM accumulates on the filter, the laser transmittance decreases. The instrument is calibrated to convert this decrease in transmittance to a real-time concentration of elemental carbon in the air.

Abstract: A device for generating exhaust gas including a exhaust gas channel and a system. The system includes: a plurality of Bragg gratings distributed in positions transversely to the direction of flow of an exhaust gas at the end of the exhaust gas channel; an optical wave guide structure includes at least one optical wave guide and the Bragg gratings; and a heating device arranged adjacently to the Bragg gratings and through which the Bragg gratings are subjected to heat, or a cooling device arranged adjacently to the Bragg gratings, through which the Bragg gratings can be subjected to cold. The optical wave guide structure and the heating device or the cooling device are arranged at the end of the exhaust gas channel at a distance from an outlet of the exhaust gas into the surroundings of the device.

Abstract: A method includes providing an exhaust stream for an internal combustion engine, where the exhaust stream is fluidly coupled to an aftertreatment component. The method includes optically determining an amount of an exhaust gas constituent in the exhaust stream. The method further includes modifying a model stored on a computer readable medium in response to the amount of the exhaust gas constituent. The model is an engine NOx generation model, a catalyst NOx storage model, a catalyst NOx conversion model, a catalyst NO to NO2 conversion model, a catalyst conversion efficiency model, an engine soot generation model, and/or a urea hydrolysis model.

Abstract: A system and a method for detecting the existence of a target substance, the system includes a laser with a broad spectral output and a detector for detecting an absorption spectrum of a laser beam from the laser. The method includes emitting a laser beam into the atmosphere using a laser light with a broad spectral output; measuring the absorption spectrum of said laser beam; comparing the absorption spectrum to known absorption spectrums for target substances using a detector; and detecting the existence of a target substance.

Abstract: A system for detecting engine fluid constituents includes an engine having a sample channel having a conduit for a working engine fluid. The system includes an electromagnetic (EM) source that emits EM radiation through a first metal tube, where the EM radiation is EM energy at a wavelength of interest. The system further includes an EM detector that receives a remainder radiation through a second metal tube, the remainder radiation including the remaining EM radiation after passing through the sample channel. The system includes a controller that determines a composition indicator signal representative of an amount of a constituent in the working engine fluid in response to a strength of the remainder radiation, and determines a concentration of a component of interest according to the composition indicator signal.

Abstract: An exhaust gas analyzer capable of real-time analysis of the concentration, temperature, and the like of an exhaust gas component in a cross-section of an exhaust path in a spot-wise manner reduces analysis cost. An exhaust gas analyzer (10) comprises sensor units (11) to (14) disposed along the exhaust path, which comprises an exhaust manifold (3) for the engine (2) discharging exhaust gas, an exhaust tube (4), a first catalyst device (5), a second catalyst device (6), a muffler (7), and an exhaust pipe (8). Each sensor unit includes an optical fiber (25) for irradiating the exhaust gas with laser light, and a detector (26) for receiving the laser light emitted by the optical fiber that has been transmitted through the exhaust gas. Based on the laser light received by the detector, the condition of an exhaust gas component, such as its concentration, temperature, and the like, is measured for the analysis of the exhaust gas.

Abstract: A particle detector including a chamber, a first aspirator, a sensor(s), a controller and clean air supply. The controller, when in a detecting mode, receives an indicative signal from the sensor and applies logic to the indicative signal to generate a further signal, and when in the purge mode controls substantial purging of the chamber of sample fluid with clean fluid from the clean fluid supply. The controller receives the indicative signal when the chamber is so purged and if necessary adjusts the logic in response thereto.

Abstract: A particle detection unit including a detection chamber and a duct detector is disclosed. The duct detector is disposed within the detection chamber. The duct detector has a rod with a first and a second end where the first end is distal the second end. A reflector may be attached to the rod adjacent the first end. A sensor and emitter device may be attached to the rod and spaced apart from the reflector.

Abstract: A probe assembly for measuring the concentration of exhaust's emissions in a turbine engine. The probe assembly including a first probe member configured and operable to passively generate a beam of light wherein the wavelength of the beam of light is contingent upon the configuration of the first probe member. A second probe member positioned in the probe assembly to receive the beam of light generated by the first probe member, the second probe member configured and operable to attenuate the light passively generated from the first probe member contingent upon the gaseous species present in the exhaust emissions of the turbine engine.

Abstract: An exhaust gas analysis method comprises applying a laser beam to the exhaust gas discharged from an internal combustion engine, receiving the laser beam that has passed through the exhaust gas, and measuring the concentration of any of the components contained in the exhaust gas based on the received laser beam. The exhaust gas analysis method further comprises detecting the absorption spectrum of the laser beam absorbed in the exhaust gas by using the received laser beam, calculating the concentration of the specific gas component by using the absorption spectrum, calculating the temperature of the exhaust gas by using the absorption spectrum, calculating the pressure of the exhaust gas by using the absorption spectrum, correcting the calculated concentration of the component contained in the exhaust gas by using the calculated temperature, correcting the concentration by using the calculated pressure, and outputting the true concentration value.

Abstract: Techniques are provided for enhancing the visibility of objects located below the surface of a scattering medium such as tissue, water and smoke. Examples of such an object include a vein located below the skin, a mine located below the surface of the sea and a human in a location covered by smoke. The enhancement of the image contrast of a subsurface structure is based on the utilization of structured illumination. In the specific application of this invention to image the veins in the arm or other part of the body, the issue of how to control the intensity of the image of a metal object (such as a needle) that must be inserted into the vein is also addressed.

Abstract: In one aspect, the present invention relates to a device for remote sensing of emissions of a vehicle driven on a road. In one embodiment, the device includes a source for emitting a beam of light and transmitting the emitted light through an exhaust plume emitted from the vehicle to the surface of a lane of the road on which the vehicle is driven, wherein the transmitted light is scattered at the surface of the lane; a detector for receiving at least one portion of the scattered light scattered from the surface of the lane; and a processor for processing the received light therein to provide one or more spectra of the received light so as to determine components and concentrations of the exhaust plume. The source and the detector are located in the same side of the road.

Abstract: The attenuation and other optical properties of a medium are exploited to measure a thickness of the medium between a sensor and a target surface. Disclosed herein are various mediums, arrangements of hardware, and processing techniques that can be used to capture these thickness measurements and obtain three-dimensional images of the target surface in a variety of imaging contexts. This includes general techniques for imaging interior/concave surfaces as well as exterior/convex surfaces, as well as specific adaptations of these techniques to imaging ear canals, human dentition, and so forth.

Abstract: A photoacoustic detector for measuring a concentration of fine dust particles in gas. The detector includes at least one acoustic sensor for detecting an acoustic signal. Additionally, the detector includes a pulsed light source for providing excitation light having a configurable pulse length and a configurable pulse repetition rate, wherein by changing the pulse length and/or the pulse repetition rate, a size distribution of the fine dust particles can be determined.

Abstract: A probe for gas analysis is provided in a pipe through which sample gas flows. The probe includes a tubular member and one or more sample gas inflow portions. The tubular member is disposed to cross a flow of the sample gas, and includes a measurement field to which the sample gas is introduced. The one or more sample gas inflow portions are provided in the tubular member. The sample gas flows around, and flows into the measurement field through the one or more sample gas inflow portions.

Abstract: According to example configurations herein, a system includes an inertial filter, a temperature controller, and analyzer. The inertial filter has multiple ports including a first port, a second port, and a third port. A sample gas flows between the first port and the third port of the inertial filter. The second port of the inertial filter outputs a portion of the gas flowing between the first port and the second port. The temperature controller controls a temperature of the inertial filter and/or the gas flowing through the inertial filter. The analyzer receives the portion of the gas flow outputted by the second port of the inertial filter and produces a value indicative of a concentration of sulfur trioxide in the portion of the gas flow.

Abstract: In a cleaning system, dust stored in a dust box is suspended in air introduced into the dust box through a first opening formed through a robot cleaner, and is then discharged to a second opening formed through a maintenance station through the first opening of the robot cleaner.

Abstract: The present invention describes a system for accurately measuring the concentration of a substance within a filter housing. A concentration sensor and a communications device are coupled so as to measure and transmit the concentration of a particular substance within the filter housing while in use. This system allows the operator to certify the integrity of the filters within the filter housing at the customer site without additional equipment. In one embodiment, a tracer gas, such as helium or hydrogen, is added to a carrier and injected into the system. The concentration of tracer gas at a specific operating transmembrane pressure is indicative of bubble pointing specific pores in the filter. This test will give a more sensitive indication of the bubble point and the presence of defects than a standard diffusion test. In a second embodiment, two gasses, in a known ratio, are introduced into the filter housing.

Abstract: A multi-frequency photoelectric smoke detector includes a multi-frequency, source and an multi-frequency sensing array. The array can be part of a solid state camera which can be used to sense scattered multi-frequency light. Multiple wavelength signals, red, blue green for example, emitted by the camera can be analyzed to determine a degree of airborne particulate matter in a sensing region between the source and the array.

Abstract: A system for detecting engine fluid constituents includes an engine having a sample channel having a conduit for a working engine fluid. The system includes an electromagnetic (EM) source that emits EM radiation through a first metal tube, where the EM radiation is EM energy at a wavelength of interest. The system further includes an EM detector that receives a remainder radiation through a second metal tube, the remainder radiation including the remaining EM radiation after passing through the sample channel. The system includes a controller that determines a composition indicator signal representative of an amount of a constituent in the working engine fluid in response to a strength of the remainder radiation, and determines a concentration of a component of interest according to the composition indicator signal.

Abstract: Values for one or more particle properties, such as an aerosol asymmetry parameter g, can be measured directly using a detector that measures scattered light. The detector can comprise two or more diffusers coupled to optical sensors responsive to scattered light that is incident on the surfaces of the diffusers. One or more weighing functions can be obtained based on diffuser geometry. In an example, the diffusers correspond to quadrants of a circular toroid.

Abstract: A system for measuring size segregated mass concentration of an aerosol. The system includes an electromagnetic radiation source with beam-shaping optics for generation of a beam of electromagnetic radiation, an inlet sample conditioner with adjustable cut-size that selects particles of a specific size range, and an inlet nozzle for passage of an aerosol flow stream. The aerosol flow stream contains particles intersecting the beam of electromagnetic radiation to define an interrogation volume, and scatters the electromagnetic radiation from the interrogation volume. The system also includes a detector for detection of the scattered electromagnetic radiation an integrated signal conditioner coupled to the detector and generating a photometric output, and a processor coupled with the conditioner for conversion of the photometric output and cut-size to a size segregated mass distribution.

Abstract: A smoke detector contains a radiation source for transmitting an illuminating radiation having a time sequence of radiation pulses, a radiation detector for receiving measurement radiation impinging on the radiation detector after at least partial scattering of the illuminating radiation, an amplifier circuit for amplifying an output signal of the radiation detector, an analog to digital converter having a sample and hold circuit for converting an analog output signal of the amplifier circuit into a digital measurement value, and a control device coupled to the radiation source and the sample and hold circuit. The control device is equipped for controlling the radiation source and the sample and hold circuit such that the time of a sampling point in time of the sample and hold circuit relative to a radiation pulse depends on the duration of the radiation pulse. A method for calibrating the described smoke detector is also revealed.

Abstract: A method and device for measuring trace levels of particles in an air sample is described. A device operating in a gradiometer configuration with two cavities built from a monolithic structure and utilizing a single probe laser, provides common mode subtraction of acoustic, vibrational, laser intensity and other noise sources, which allows sensitivity more closely approaching the quantum limit. Differential measurements between the two cavities occur simultaneously, which reduces errors due to cavity drift. Absorptive gradiometry can therefore provide noise immune detection for trace gasses, including broad linewidth absorbers where frequency-noise immune schemes are not practical. Differential measurements can be used for background subtraction, sensing vapor plume gradients and determining vapor plume propagation direction.

Abstract: The present disclosure relates to measurement techniques utilizing laser induced incandescence, and specifically to laser induced incandescence measurement techniques utilizing a hollow core fiber.

Abstract: A sensor head for a dry powder agent according to an exemplary aspect of the present disclosure includes a housing defined along an axis along which light is communicated, the housing defines a multiple of apertures transverse to the axis, the multiple of apertures in communication with a measurement volume along the axis. A mirror is within the housing to reflect the light through the measurement volume.

Abstract: A particulate detector (10) comprises a radiation source (12) arranged to emit radiation in at least first and second predetermined wavebands towards a sampling region (18) suspected of containing particulates, and a detection element (14), shielded from the radiation source (12), and arranged to detect radiation from the sampling region (18) at least first and second instances. The radiation source (12) is such that the emissions in the wavebands temporarily overlap. The detector is such that, at the instances at which the radiation is detected, the relative contributions from the emissions in each predetermined waveband are distinguishable, thereby allowing characteristics of the particulates to be determined. The radiation source (12) may comprise a light emitting diode (24).

Abstract: A method includes providing an exhaust stream for an internal combustion engine, where the exhaust stream is fluidly coupled to an aftertreatment component. The method includes optically determining an amount of an exhaust gas constituent in the exhaust stream. The method further includes modifying a model stored on a computer readable medium in response to the amount of the exhaust gas constituent. The model is an engine NOx generation model, a catalyst NOx storage model, a catalyst NOx conversion model, a catalyst NO to NO2 conversion model, a catalyst conversion efficiency model, an engine soot generation model, and/or a urea hydrolysis model.

Abstract: A system for the monitoring and/or controlling emission levels of nitrogen oxide and a reductant from a stream of combustion exhaust, wherein the internal combustion engine includes a SCR unit disposed in the stream of combustion exhaust between an upstream conduit and a downstream conduit, the SCR unit having a catalyst that is configured to catalytically reduce nitrogen oxides contained in the combustion exhaust to elemental nitrogen in the presence of a reductant and oxygen, and wherein the internal combustion engine further includes a reductant injector; the system comprising: a laser absorption spectroscopy unit that is disposed in the downstream conduit and configured to measure the concentration level of at least nitrogen oxide and the reductant in the exhaust; and a control unit.

Abstract: The invention relates to a process and a monitoring device for monitoring an equipment unit, carried out by a processing device in the monitoring device. The process comprises reading at least one sensor signal and determining, on the basis of the at least one sensor signal, whether the equipment unit has been subjected to an unacceptable stress. If the equipment device has been subjected to an unacceptable stress, a start-up lock for the equipment unit is enabled, and lock status information is stored. The step of determining whether the equipment unit has been subjected to an unacceptable stress may comprise criteria that are dependent upon whether the monitoring device is operating in a low-power mode or a normal power mode. When a signal is received that indicates that the equipment unit is to be started up, it is determined whether the start-up lock has been enabled. If it has been enabled, a warning is activated.

Abstract: A method of obtaining a fugitive emission flux measurement of airborne matter is provided. The method involves measuring the airborne matter along one or more than one measurement surface that spans the fugitive emission using two or more than two measurement beam paths where each of the two or more than two measurement beam paths are parallel to each other, or substantially parallel to each other, and determining a mass per unit length measurement for the measurement surface, determining a representative wind velocity at or near the one or more than one measurement surface, and calculating the fugitive emission flux of the airborne matter in mass per unit time using the mass per unit length determination and representative wind velocity.

Abstract: A photoelectric smoke detector may detect presence of smoke by utilizing a light emitting element and a light receiving element whose optical axes intersect with each other. The photoelectric smoke detector may include a casing for storing the light emitting element and the light receiving element. Inlet and outlet ports may be respectively provided in one and the other sides of the casing, the inlet and outlet ports bringing air flow into the casing. Rectifying light blocking means may be provided contiguously with each of the inlet and outlet ports, the rectifying light blocking means preventing entry of disturbance light into an interior space and forming a flow line of smoke extending from one or the other inlet and outlet port to the other or the one inlet and outlet port such that the flow line passes through a detection area by the light emitting element and the light receiving element.

Abstract: An exhaust gas analyzer of the present invention includes a sensor unit 11 installed in an exhaust path from an engine, applies laser light to exhaust gas emitted from the engine and receives laser light that has passed through the exhaust gas so as to measure the concentration of a component contained in the gas based on the received laser light. To an aperture 16 formed in a sensor base 15 of the sensor unit 11, an adjustment ring 40 in a circumferential face of which small holes 41 serving as a laser light passage portion is formed and whose inner circumferential face serves as an exhaust gas passage opening 21 is detachably fitted, whereby the sensor unit can be attached so as to conform to different inner diameters of exhaust tubes.

Abstract: An apparatus and method for estimating size segregated aerosol mass concentration in real time and using a single detector. A beam of electromagnetic radiation is passed through a particle stream made of a test or field aerosol. The single detector outputs an electrical signal proportional to the electromagnetic radiation scattered thereupon. The electrical signal may be conditioned to produce an integrated signal for measuring radiation scattered from all the particles in the interrogation volume, a pulse height from an individual particle within the volume, and/or a time-of-flight measurement from the individual particle. The integrated signal can be correlated to particle mass concentration. The pulse height signal and the time-of-flight signal may be converted to infer the size of the individual particle. Attendant size distributions for the particle sizes may also be obtained. Using known or assumed particle properties, the mass concentration may be estimated from the size distribution.

Abstract: A sensor having a detecting part for detecting an environmental value representing change in physical amount of circumference environment by a fluid flowing into externally and a controlling part for discriminating abnormality in circumference environment based on the environmental value detected by the detecting part. A separating plate is provided inside a housing so as to separate two spaces in the height direction. A detection unit is provided in one space and a sounding body is provided in the other space. Apertures are provided in a side wall, thereby opening one space to the outside environment and letting the fluid to be measured flow into the space. Then, a flow path is formed inside the space in the housing, from the side wall forming the housing toward the detection unit, thereby proactively channeling the fluid to the detection unit.

Abstract: The photoelectric smoke sensor includes a casing member 1 having an internal space S formed by a labyrinth wall 1b and an opening 6 communicating with the internal space S on a setting-face side; and a printed board 8 placed on the setting-face side of the casing member 1 and having a hole 8a opposed to the opening 6 of the casing member 1. The light emitting element 2 and the light receiving element 4 are mounted on the printed board 8 in such a fashion that the optical axes of the light emitting element 2 and the light receiving element 4 cross each other on one plane that is substantially parallel to an opening plane of the opening 6. The photoelectric smoke sensor can be reduced in both size and cost with a simple construction.