Fire and smoke detection and control system
First Claim
1. In a fire detection system that includes a light reflection type smoke detector having a light emitter from which light propagates along a propagation path and a light sensor positioned at an angular offset relative to the propagation path, the light sensor receiving light emitted by the light emitter and reflected by smoke particles passing across the propagation path, and the angular offset being of greater measure for optimal detection of smoke particles produced by a flaming fire than that for optimal detection of smoke particles produced by a nonflaming fire, a method of providing a fire detection system that is capable of accurately detecting flaming and nonflaming fires in a spatial region, comprising:
- fixing the angular offset of the light reflecting type smoke detector to a relatively small angle for detecting and producing a first signal representative of a smoke particle concentration produced by a nonflaming fire;
providing a carbon dioxide (CO2) detector for detecting and producing a second signal representative of a CO2 concentration produced by a flaming fire; and
applying the first and second signals to processing circuitry that processes the first and second signals to determine whether either a flaming or a nonflaming fire condition is present in the spatial region and to produce an alarm signal in response to a determination of the presence of either condition.
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Accused Products
Abstract
A fire detection system combines a CO2 gas detector with a smoke detector. Logic circuitry combines the outputs of both detectors to minimize false alarms and provide a rapid response time. In a preferred embodiment the need for periodic cleaning is reduced. In a further preferred embodiment, two alarms indicative of two different types of fires, for example flaming fires and nonflaming fires are available. A map of flaming fire and smoke may be assembled by the system to guide the firefighters. In a yet another preferred embodiment, a tentative fire alarm indication disables a local air conditioning system thereby helping to isolate and control any existing fire.
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Citations
34 Claims
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1. In a fire detection system that includes a light reflection type smoke detector having a light emitter from which light propagates along a propagation path and a light sensor positioned at an angular offset relative to the propagation path, the light sensor receiving light emitted by the light emitter and reflected by smoke particles passing across the propagation path, and the angular offset being of greater measure for optimal detection of smoke particles produced by a flaming fire than that for optimal detection of smoke particles produced by a nonflaming fire, a method of providing a fire detection system that is capable of accurately detecting flaming and nonflaming fires in a spatial region, comprising:
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fixing the angular offset of the light reflecting type smoke detector to a relatively small angle for detecting and producing a first signal representative of a smoke particle concentration produced by a nonflaming fire; providing a carbon dioxide (CO2) detector for detecting and producing a second signal representative of a CO2 concentration produced by a flaming fire; and applying the first and second signals to processing circuitry that processes the first and second signals to determine whether either a flaming or a nonflaming fire condition is present in the spatial region and to produce an alarm signal in response to a determination of the presence of either condition. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of distinguishing aberrant light source operation from changes in smoke or CO2 concentration levels measured by a fire detection system including a smoke detector and a CO2 detector, comprising:
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providing a smoke detector having a light detector that detects light within a first wavelength range to produce a first signal representative of smoke concentration in a spatial region; providing a CO2 detector having a light detector that detects light within a second wavelength range to produce a second signal representative of CO2 concentration in the spatial region; operatively associating with the smoke detector and the CO2 detector a light source that emits light within an emission wavelength range encompassing at least a portion of each of the first and second wavelength ranges; and processing the first and second signals to detect the existence of aberrant light source operation by determining whether the first and second signals represent contemporaneous instances of mutual diminution of intensity of light incident on the smoke and CO2 detectors. - View Dependent Claims (10, 11, 12)
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13. A fire detection system having a prolonged operational lifetime, comprising:
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a photoelectric smoke detector producing a first signal representing a measured concentration of smoke in a spatial region in which there is an actual concentration of smoke, the photoelectric smoke detector having an alarm threshold value representing a predetermined concentration of smoke; correction circuitry that offsets the first signal by a drift tolerance amount to produce a corrected first signal that more accurately represents the actual concentration of smoke in the spatial region; a CO2 detector producing a second signal representing a concentration of CO2 in the spatial region; and either one of the corrected first signal or the second signal causing production of an alarm signal whenever any member criterion of a predetermined set of criteria is satisfied, one member criterion in the predetermined set including a condition in which the corrected first signal exceeds the alarm threshold value for a predetermined time, the alarm threshold value and predetermined time being coordinated to cause no alarm signal production in response to actual concentrations of smoke that do not represent typical instances of anticipated sources of fire. - View Dependent Claims (14, 15, 16, 17)
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18. A fire detection system that is capable of detecting flaming and nonflaming fires, comprising:
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a smoke detector producing a first signal representing a smoke concentration in a spatial region;
a CO2 detector producing a second signal representing a rate of change of a concentration of CO2 in the spatial region; andelectrical circuitry producing an alarm signal in response to a result of a formulation to which the smoke concentration represented by the first signal and the rate of change of CO2 concentration represented by the second signal contribute to characterize a fire condition existing in the spatial region. - View Dependent Claims (19, 20, 21, 22, 23)
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24. A fire detection system comprising:
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a light reflection type smoke detector having a light emitter from which light propagates along a propagation path and a light sensor positioned at an angular offset relative to the propagation path, the angular offset being fixed to a relatively small angle for detecting and producing a first signal representing a smoke concentration produced by a nonflaming fire in a spatial region; a CO2 detector producing a second signal representing a concentration of CO2 in the spatial region; electrical circuitry for receiving and retransmitting the first and second signals; and a fire alarm control panel communicatively coupled to the electrical circuitry for receiving the retransmitted first and second signals and producing an alarm signal whenever any member criterion of a predetermined set of criteria for the first and second signals is satisfied. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32, 33, 34)
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Specification