US3874795A - Smoke detector - Google Patents

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Publication number
US3874795A
US3874795A US367260A US36726073A US3874795A US 3874795 A US3874795 A US 3874795A US 367260 A US367260 A US 367260A US 36726073 A US36726073 A US 36726073A US 3874795 A US3874795 A US 3874795A
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instrument
light
space
source
monitored
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US367260A
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English (en)
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David Roy Packham
Leonard Gibson
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Commonwealth Scientific and Industrial Research Organization CSIRO
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Commonwealth Scientific and Industrial Research Organization CSIRO
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/47—Scattering, i.e. diffuse reflection
    • G01N21/49—Scattering, i.e. diffuse reflection within a body or fluid
    • G01N21/53—Scattering, i.e. diffuse reflection within a body or fluid within a flowing fluid, e.g. smoke
    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B17/00—Fire alarms; Alarms responsive to explosion
    • G08B17/10—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means
    • G08B17/103—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means using a light emitting and receiving device
    • G08B17/107—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means using a light emitting and receiving device for detecting light-scattering due to smoke
    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B17/00—Fire alarms; Alarms responsive to explosion
    • G08B17/10—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means
    • G08B17/11—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means using an ionisation chamber for detecting smoke or gas
    • G08B17/113—Constructional details

Definitions

  • ABSTRACT A smoke monitoring instrument having first and second chambers, each with a respective photodetector means, a light source common to both chambers and positioned to illuminate part of the interior of each chamber, means for conveying a first air sample from the space to be monitored into said part of the first chamber, means for conveying a second air sample from outside the space into said part of the second chamber, each photodetector means being arranged to receive light from the source which is scattered by its respective air sample but not to receive light directly from the source whereby the effects of suspended material in the first sample originating from outside the space to be monitored can be observed or removed [56] References Cited from the output of the instrument.
  • SMOKE DETECTOR This invention relates to early warning fire detectors, and has for its object the provision of means for detecting the presence of smoke particles (or similar light scattering material for example. airborne dust hereafter included within the term smo.ke”) in gases such as air.
  • the invention provides a smoke monitoring instrument having first and second chambers, each with a respective photodetector means, a light source common to both chambers and positioned to illuminate part of the interior of each chamber means for conveying a first air sample from the space to be monitored into said part of the first chamber, means for conveying a second air sample from outside the space into said part of the second chamber, each photodetector means being arranged to receive light from the source which is scattered by its respective air sample but not to receive light directly from the source.
  • the light source is preferably a flash tube operated periodically to illuminate the air samples with an intense flash of light
  • the photodetector means are preferably photomultiplier tubes.
  • the source of light may be continuous rather than intermittent but the latter is preferred because less energy is required to power the lamp and less heat is developed in the lamp.
  • advantage may be taken of the period when the source is inactive to monitor noise levels in the instrument so that more accurate output is possible with appropriate compensation.
  • the outputs from the detectors are recorded directly, or subtracted one from the other and the difference signal recorded.
  • the record should be such that short-interval peaks of smoke, typical of cigarette smoke or the like can be distinguished from the steady build-up of smoke which accompanies the outbreak of a serious fire. With such a record, it is possible to set the sensitivity of the instrument to detect smoke levels well below those typical of conventional level-triggered devices. An alert may be set to trigger at light obscurations as low as 0.02 percent per meter.
  • a supervisor may then investigate the incident by inspecting the record for instance, in the form of traces on a chart from a pen recorder and take appropriate action.
  • automatic circuitry may be set into operation to interpret the record suitably in the form of stored charges on capacitors or the like.
  • a particularly advantageous feature of the instrument according to this aspect of the invention resides in its ability to allow for the effects of outside air pollution.
  • Rising air pollution by smoke which may occur during the morning in industrialized localities, or be caused by bush fires, can bring the scattering coefficient of outside air into the range where the instrument will signal an alert.
  • Outside air for the purposes of this specification, refers to the air used to ventilate the space being monitored, and will normally be the open air surrounding the building. While smoke is building up in the outside air, it will in the absence of a fire inside have a larger light scattering coefficient than the inside air. When the outside smoke level drops again, however, smoke will have accumulated inside, and will register as having a scattering coefficient relative to the now cleaner outside air sufficiently high to trigger an alert.
  • the instrument is particularly effective if it is coupled into a forced air circulation or conditioning system.
  • the first air sample is drawn from the exhaust air duct of the system,- and the second air sample directly from outside, or from the inlet air duct of the system.
  • the instrument may be made sufficiently sensitive that, despite the diluting effect of large volumes of air passing into the exhaust duct, small quantities of smoke.
  • the invention also provides a method of detecting the generation of smoke associated with a fire hazard in a space to be monitored. comprising the steps of drawing a first sample of air from the space to be moni tored. drawing a second sample of air from outside said space. exposing both samples to a source of light and generating two signals, each related to the amount of light scattered by a respective one of said samples. and storing a record of said signals over a period of time.
  • FIG. 1 is a diagrammatic representation of one form of the instrument according to the invention.
  • FIG. 2 shows a cross-section of the instrument at 22
  • FIG. 3 is a diagrammatic representation of another form of the instrument according to the invention.
  • FIG. 4 is an airflow diagram showing how the instrument is connected to the space to be monitored
  • FIG. 5 is a block diagram of a circuitfor operating the instrument
  • FIG. 6 is a more detailed diagram of part of the de tecting circuit shown in FIG. 5;
  • FIG. 7 is a graphical representation showing various features of the output from the instrument.
  • the instrument shown in FIG. 1 comprises two lighttight chambers. 1 and 1', the internal surfaces of which are coated with optical black paint or the like to minimize reflections. Inside each chamber are located a series of knife edge light baffles. 2-9 and 2'-9', which restrict the field of view of photomultipliers 10,10. to volumes 1, 1'.
  • the light baffles are also coated with optical black paint to limit reflections. and have central apertures graded upwardly from baffles 3-8 (38).
  • Baffles 2, 2' have apertures the same size as baffles 3, 3', and baffles9, 9, have smaller apertures than baffles 8, 8', to form respective light-traps at the end of each chamber.
  • FIG. 2 shows baffles 6 and 6' in a cross-section of the instrument taken at 2-2 in FIG. 1.
  • Central apertures 11, 11 define the fields of view of the photodetectors l0, l. and allow air to pass from inlets 12, 12' to outlets 13, 13.
  • Further apertures 14, 14 in light baffles 6 and 6' are provided for extra air circulation to allow a more even distribution of air within the chambers.
  • Similar air circulation apertures are provided in light baffles 5, 7 and 7'.
  • the light baffles may be replaced wholly or in part by one or more tubes positioned to define similar fields of view for the light detector.
  • Xenon flash tube 15 is provided in a common wall 16 between the chambers in such a way that flashes of light, transmitted through light diffusing windows 17, 17, for example made of opal glass, can be scattered by smoke in the air samples in both chambers into respective photodetectors 10, 10'.
  • Casing 18, also in common wall 16, houses a capacitor bank which in operation discharges through lamp 15.
  • the instrument shown in FIG. 3 is essentially the same in operation as that described previously but its physical arrangement and construction include a number of features to improve performance and reduce manufacturing and maintenance costs. Parts in this form which are common to that described previously 1 have the same reference numerals.
  • the two chambers 11, 11 are located on opposite sides of a plate 50 which forms the upper part of a housing for the instrument.
  • the upper part of the housing with the chambers attached can be readily removed to allow access to the flash tube 15 and photodetectors 10, 10 for replacement.
  • the chambers 11 and 11 are formed by sheet metal structures about 55 cm in s length. 5 cm across, and 8 cm in depth. Both the inside and outside of the structures are painted with optical black paint.
  • Each chamber, 11, 11 includes baffles 51,1
  • baffles 51, 51 and 53, 53 are provided with centralaperatures 57, 57 and 58, 58 which define the field .of
  • openings 60, 60 being surrounded by short branch sec- J tions 61, 61 which project from the sheet metal structures defining the chambers 11, 11".
  • the branch sec-- tions are terminated by diffusing windows 19, 19
  • the spaced plates are found to provide a better source of diffused light than a single plate or a single plate of equivalent thickness.
  • the majority of light emanating from the plates 62, 62. is inclined relative to the longitudinal axis of the chambers 11, 11. and more scattered light for a given smoke concentration can be detected by the detector because more light is scattered in the direction of the incident light beam 3 than in other directions.
  • the area illuminated by the lamp 15 through the 7 plates 62, 62 and 63, 63' is determined by apertures 65, 65' and 66, 66' in baffles 56, 56 and 61,61 respectively and extremities are shown by lines 64, 64, and the area between the intersection of lines 59,59.
  • the position of the air inlets and outlets to the chambers is not critical but in this arrangement the inlets 12, 1 l2 and outlets 13, 13 are at the top of the chambers 11, 11 and located either side of the sample volume
  • the baffles 52, 52'; 54, 54'; 55, 55'; are provided to reduce internal reflections within the chambers 11, 11' without taking any part in the definition of the sample volumes 67, 67.
  • Oblique baffles 68, 68 are provided and function as 12 to chamber 1 is connected to the exhaust air duct 1 21 from space 20, and outlet 13 is exhausted (to atmosphere if convenient).
  • a blower 22 may be connected to inlet 12 to force air from duct 2 into chamber 1.
  • Inlet 12 to chamber 1 is connected to ventilation inlet duct 23, or directly to the outside atmosphere, again via a blower, 24, if desired.
  • Outlet 13' is also exhausted to atmosphere if convenient.
  • Blowers 22 and 24 may be combined into a single blower following outlets l3, 13 if negative pressure inside instrument 19 does not give rise to serious inaccuracies due to leakage of air into either chamber.
  • FIG. shows how clock pulses from Clock Pulse Generator 25 govern the operation of Trigger and Gate Pulse Width circuit 26 which in turn causes the High Voltage Discharge Supply circuit, 27, to discharge through Xenon flash tube 28.
  • the frequency of pulses (and thus flashes) is not critical; frequency of 1 pulse per second has been found to be satisfactory but frequencies of 10 per second may readily be used.
  • the duration of the pulse from the circuit 26 is not critical but a pulse duration of 50 us has been found to be satisfactory.
  • Light scattered into Photomultiplier 29 (corresponding to Photodetector 10 in FIG. 1) causes an output signal which is amplified in Amplifier 30 and synchronously detected and stored in Synchronous Integrator and Hold Circuit, 31.
  • the latter circuit is governed by circuit 26 so that a charge pro portional to the output from the photodetector during an interval corresponding to the flashing time of the Xenon lamp 28 is stored on a capacitor.
  • This output will include a component of noise, and during the following period where the lamp is quiescent, noise from the photodetector is averaged over the whole period and stored in another capacitor in circuit 31.
  • the charges on both capacitors are combined in such a way that the average noise charge is subtracted from the charge representing the scattered light signal plus noise, leaving a closer approximation to the scattered light signal than is possible with an uncompensated detector.
  • the resultant signal is fed into Buffer 32, and thence into a first channel of a Chart Recorder 33, or a Difference Amplifier 34 (or both).
  • the other input to the difference amplifier shown diagrammatically at 35, is from a second channel (not shown) derived from a photomultiplier corre sponding to the photomultiplier 10 in FIG. 1 and brought through a similar circuit to that for photomultiplier 29.
  • the output from the second channel may be recorded on a second channel of Chart Recorder 33, and the signal from the difference amplifier 34 may be recorded on a third channel of Chart Recorder 33.
  • FIG. 6 A more detailed diagram of one form of the synchronous lntergrate and Hold Circuit 31 is shown in FIG. 6.
  • a pair of field effect transistors F1 and F2 of opposite channel doping are used to control storage of charge on storage capacitors Cl and C2 respectively.
  • the capacitors Cl and C2 are connected to the output of amplifier 30 through resistor R, the time constants RC and RC being much greater than the pulse duration to give an integrating effect.
  • the capacitor C stores charge throughout the whole cycle period and thus its charge will be representative of the scattering and noise levels.
  • the capacitor C on the other hand, does not store charge during the flashing period but stores at other times and hence its charge is representative of noise.
  • the capacitors C, and C are effectively in series from the point of view of the output and hence their contributions to the output level will be subtracted, and thus the noise is effectively cancelled out.
  • FIG. 7 shows a series of traces depicting various conditions which may appear in the output from chart recorder 33, showing voltage on the vertical scale and time on the horizontal.
  • the traces are diagrammatic only, and in practice the events shown will normally take place over a considerable time, with long periods of uniform signal levels being recorded between events.
  • trace A corresponds to the inside air condition monitored in chamber 1
  • trace B corresponds to the outside air condition monitored in chamber 1;
  • trace C corresponds to the difference Amplifier 34.
  • other parameters which may have a bearing on the interpretation of these traces may also be recorded, for example, mains voltage.
  • the traces may be recorded in situ, but in many circumstances it may be desirable to record them at a central monitoring station serving a number of installations.
  • the signal levels may be transmitted along telephone lines, for example, as tones. the frequencies of which are respectively related to the amplitudes of the signals to be recorded.
  • traces A, B and C are all shown as beginning at their respective zero levels, indicating clean air inside and outside the space to be monitored.
  • Events D and E relatively sharp peaks in the measured scattering level of the inside air, are typical of the temporary rises causes by exhalations of smoke by a person smoking a cigarette, for example, particularly if he is near the ventilation exhaust duct of the air circulation system.
  • Peak F indicates a calibrating step, which may be the firing of three fusees together each fusee generating about 20 mg of smoke in the centre of the space being monitored. In one working monitoring arrangement, it has been found desirable to actuate a yellow" alert at this calibrating level. This alert is intended merely to draw a supervisors attention to the instrument, as it does not necessarily indicate a fire.
  • the triggering level may be set at a scattering coefficient [b (scat)] level of about 2.2 X 10' m, where b (scat) is the fraction of incident light scattered by the sample (integrated for all angles between incident and scattered light directions). This corresponds to a meteorological visual range of about 18 kilometres.
  • More urgent alert signals may also be designed to operate at higher scattering levels than the yellow. For example, an orange alert, initiating an investigation at the building being monitored, could be set at a b (scat) of 4.4 X 10 m (visual range, about 9 km); and a red" alert, calling the Fire Brigade and operating fire control systems, could be set at a b (scat) of about 7 X 10 m (visual range, about 5.5 km).
  • the red alert level in particular, would have to be adjusted to suit the particular circumstances of the building being monitored.
  • Event G denotes the onset of a real fire, and it can be seen that the yellow level (set, for example, at about 1 volt on the recorder) is passed shortly after the first traces of smoke are generated. A supervisor looking at the trace could immediately see its steadily rising form. and take prompt action.
  • the yellow level set, for example, at about 1 volt on the recorder
  • Line H separates the traces for a later incident, shown for convenience on a much contracted time scale.
  • outside smoke levels begin to rise, causing a negative swing in the difference signal.
  • J the inside air begins to show significant signs of increasing scattering caused by smoky air from outside accumulating inside.
  • the difference signal returns towards zero, but at point K, where the outside air has cleared.
  • the difference signal goes positive until the smoky air inside is cleared.
  • an additional signal, L will appear and trigger the appropriate alerts.
  • a smoke monitoring instrument having first and second chambers. each with a respective photodetector means, a light source common to both chambers and positioned to simultaneously illuminate part of the inte rior of each chamber, means for conveying a first air sample from the space to be monitored into said part of the first chamber, means for conveying a second air sample from outside the space into said part of the second chamber, each photodetector means being arranged to simultaneously receive light from the source which is scattered by its respective air sample but not to receive light directly from the source.
  • each photodetector means comprises a light sensitive element and a detector circuit responsive thereto and operable to produce an output signal representative of the amount of light received by the light sensitive element.
  • An instrument as claimed in claim 3 including means to produce a differential output signal, being a signal derived from the difference of the output signals of the detector circuits.
  • each detector circuit includes first and second storages, the first storage being operable to store a signal representative of the light received by its associated light sensitive element during the time the flash tube is operated and during the time the flash tube is not operated, the second storage being operable to store a signal representative of the light received by its associated light sensitive element during the time the flash tube is not operated, said output signal of the detector circuit being derived from the difference of the signals stored in the first and second storages, whereby noise signals are reduced.
  • An instrument as claimed in claim ⁇ including alarm circuitry operable to produce alarm signals which are dependent upon the output signal levels of.
  • first and second chambers comprise apair of spaced elongate chambers, the interiors of which are optically black, and said source of light is positioned between 1 chambers, each chamber including a window adjacent i to the source.
  • a method of detecting the generation of smoke associated with a fire hazard in a space to be monitored comprising the steps of drawing a first sample of air from the space to be monitored, drawing a second sample of air from outside said space, exposing both samples simultaneously to a source of light and generating two signals simultaneously, each related to the amount of light scattered by a respective one of said samples.
  • a method as claimed in claim 16 including the step of storing a record of the signals over a period of time.

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  • Investigating Or Analysing Materials By Optical Means (AREA)
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US367260A 1972-06-06 1973-06-05 Smoke detector Expired - Lifetime US3874795A (en)

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Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4125779A (en) * 1977-07-13 1978-11-14 Chloride, Incorporated Smoke detector
US4155653A (en) * 1977-10-14 1979-05-22 The United States Of America As Represented By The Secretary Of The Navy Smoke-measuring transducer
USRE34704E (en) * 1983-10-21 1994-08-23 Cole Martin T Improved pollution detection apparatus
US5440145A (en) * 1991-10-14 1995-08-08 I.E.I. Pty. Ltd. Sampling chamber for a pollution detector
US20060261967A1 (en) * 2002-08-23 2006-11-23 Marman Douglas H Smoke detector and method of detecting smoke
US20140197956A1 (en) * 2011-06-22 2014-07-17 Xtralis Technologies Ltd. Particle detector with dust rejection
US8907802B2 (en) 2012-04-29 2014-12-09 Valor Fire Safety, Llc Smoke detector with external sampling volume and ambient light rejection
US8947244B2 (en) 2012-04-29 2015-02-03 Valor Fire Safety, Llc Smoke detector utilizing broadband light, external sampling volume, and internally reflected light
US9140646B2 (en) 2012-04-29 2015-09-22 Valor Fire Safety, Llc Smoke detector with external sampling volume using two different wavelengths and ambient light detection for measurement correction
US9482607B2 (en) 2012-04-29 2016-11-01 Valor Fire Safety, Llc Methods of smoke detecting using two different wavelengths of light and ambient light detection for measurement correction
US20170162019A1 (en) * 2014-06-16 2017-06-08 Apollo Fire Detectors Limited Conical light absorber for smoke detector
RU179257U1 (ru) * 2017-07-03 2018-05-07 федеральное государственное автономное образовательное учреждение высшего образования "Санкт-Петербургский национальный исследовательский университет информационных технологий, механики и оптики" (Университет ИТМО) Оптический датчик дыма
US10957176B2 (en) 2016-11-11 2021-03-23 Carrier Corporation High sensitivity fiber optic based detection
US11127270B2 (en) 2016-11-11 2021-09-21 Carrier Corporation High sensitivity fiber optic based detection
US11132883B2 (en) 2016-11-11 2021-09-28 Carrier Corporation High sensitivity fiber optic based detection
US11145177B2 (en) 2016-11-11 2021-10-12 Carrier Corporation High sensitivity fiber optic based detection
US11151853B2 (en) 2016-11-11 2021-10-19 Carrier Corporation High sensitivity fiber optic based detection

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS61122553A (ja) * 1984-11-20 1986-06-10 Shimizu Constr Co Ltd クリ−ンル−ム用煙感知器

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2966092A (en) * 1958-04-29 1960-12-27 Hartridge Ltd Leslie Smokemeters
US3231748A (en) * 1961-10-30 1966-01-25 Fyr Fyter Co Smoke detector
US3313946A (en) * 1962-11-30 1967-04-11 Goodwin Smoke, flame, critical temperature and rate of temperature rise detector
US3563661A (en) * 1969-08-29 1971-02-16 Battelle Development Corp Integrating nephelometer

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2966092A (en) * 1958-04-29 1960-12-27 Hartridge Ltd Leslie Smokemeters
US3231748A (en) * 1961-10-30 1966-01-25 Fyr Fyter Co Smoke detector
US3313946A (en) * 1962-11-30 1967-04-11 Goodwin Smoke, flame, critical temperature and rate of temperature rise detector
US3563661A (en) * 1969-08-29 1971-02-16 Battelle Development Corp Integrating nephelometer

Cited By (28)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4125779A (en) * 1977-07-13 1978-11-14 Chloride, Incorporated Smoke detector
FR2400740A1 (fr) * 1977-07-13 1979-03-16 Chloride Inc Detecteur de fumee
US4155653A (en) * 1977-10-14 1979-05-22 The United States Of America As Represented By The Secretary Of The Navy Smoke-measuring transducer
USRE34704E (en) * 1983-10-21 1994-08-23 Cole Martin T Improved pollution detection apparatus
US5440145A (en) * 1991-10-14 1995-08-08 I.E.I. Pty. Ltd. Sampling chamber for a pollution detector
US20060261967A1 (en) * 2002-08-23 2006-11-23 Marman Douglas H Smoke detector and method of detecting smoke
US7564365B2 (en) * 2002-08-23 2009-07-21 Ge Security, Inc. Smoke detector and method of detecting smoke
US20140197956A1 (en) * 2011-06-22 2014-07-17 Xtralis Technologies Ltd. Particle detector with dust rejection
US9805570B2 (en) * 2011-06-22 2017-10-31 Garrett Thermal Systems Limited Particle detector with dust rejection
US9142113B2 (en) 2012-04-29 2015-09-22 Valor Fire Safety, Llc Smoke detector with external sampling volume using two different wavelengths and ambient light detection for measurement correction
US8907802B2 (en) 2012-04-29 2014-12-09 Valor Fire Safety, Llc Smoke detector with external sampling volume and ambient light rejection
US8952821B2 (en) 2012-04-29 2015-02-10 Valor Fire Safety, Llc Smoke detector utilizing ambient-light sensor, external sampling volume, and internally reflected light
US9140646B2 (en) 2012-04-29 2015-09-22 Valor Fire Safety, Llc Smoke detector with external sampling volume using two different wavelengths and ambient light detection for measurement correction
US9142112B2 (en) 2012-04-29 2015-09-22 Valor Fire Safety, Llc Smoke detector with external sampling volume using two different wavelengths and ambient light detection for measurement correction
US8947244B2 (en) 2012-04-29 2015-02-03 Valor Fire Safety, Llc Smoke detector utilizing broadband light, external sampling volume, and internally reflected light
US9470626B2 (en) 2012-04-29 2016-10-18 Valor Fire Safety, Llc Method of smoke detection with direct detection of light and detection of light reflected from an external sampling volume
US9482607B2 (en) 2012-04-29 2016-11-01 Valor Fire Safety, Llc Methods of smoke detecting using two different wavelengths of light and ambient light detection for measurement correction
US10712263B2 (en) 2012-04-29 2020-07-14 Valor Fire Safety, Llc Smoke detection using two different wavelengths of light and additional detection for measurement correction
US8947243B2 (en) 2012-04-29 2015-02-03 Valor Fire Safety, Llc Smoke detector with external sampling volume and utilizing internally reflected light
US10041877B2 (en) 2012-04-29 2018-08-07 Valor Fire Safety, Llc Smoke detection using two different wavelengths of light and additional detection for measurement correction
US10019879B2 (en) * 2014-06-16 2018-07-10 Apollo Fire Detectors Limited Conical light absorber for smoke detector
US20170162019A1 (en) * 2014-06-16 2017-06-08 Apollo Fire Detectors Limited Conical light absorber for smoke detector
US10957176B2 (en) 2016-11-11 2021-03-23 Carrier Corporation High sensitivity fiber optic based detection
US11127270B2 (en) 2016-11-11 2021-09-21 Carrier Corporation High sensitivity fiber optic based detection
US11132883B2 (en) 2016-11-11 2021-09-28 Carrier Corporation High sensitivity fiber optic based detection
US11145177B2 (en) 2016-11-11 2021-10-12 Carrier Corporation High sensitivity fiber optic based detection
US11151853B2 (en) 2016-11-11 2021-10-19 Carrier Corporation High sensitivity fiber optic based detection
RU179257U1 (ru) * 2017-07-03 2018-05-07 федеральное государственное автономное образовательное учреждение высшего образования "Санкт-Петербургский национальный исследовательский университет информационных технологий, механики и оптики" (Университет ИТМО) Оптический датчик дыма

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GB1419146A (en) 1975-12-24
JPS4952677A (cs) 1974-05-22

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