Fire sensor
First Claim
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1. A fire sensing method comprising the steps of:
- monitoring gas content in a defined area;
storing a reference spectral pattern representing a fire condition based upon combustible gases;
detecting hydrocarbon gas which is produced at a very early state of fire before ignition;
outputting a pre-alarm signal upon detection of said hydrocarbon gas indicating a potential fire condition;
performing spectral analysis of said gas content an increase in level of combustible gases;
comparing a detected spectral pattern with spectral pattern to determine whether a fire condition exists;
generating a signal to indicate the detection of fire only when both said hydrocarbon gas is detected and said detected spectral pattern corresponds to said reference pattern.
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Abstract
A fire sensing method and apparatus for detecting a fire based on the detection of a hydrocarbon gas produced before fire ignition and the detection of a second fire indicating phenomenon. Such other phenomenon may comprise the detection of temperature, radiation or combustion product gases. The detection of hydrocarbon gas may generate a pre-alarm condition which permits the use of higher sensitivity conditions for the second fire indicating phenomenon.
42 Citations
22 Claims
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1. A fire sensing method comprising the steps of:
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monitoring gas content in a defined area; storing a reference spectral pattern representing a fire condition based upon combustible gases; detecting hydrocarbon gas which is produced at a very early state of fire before ignition; outputting a pre-alarm signal upon detection of said hydrocarbon gas indicating a potential fire condition; performing spectral analysis of said gas content an increase in level of combustible gases; comparing a detected spectral pattern with spectral pattern to determine whether a fire condition exists; generating a signal to indicate the detection of fire only when both said hydrocarbon gas is detected and said detected spectral pattern corresponds to said reference pattern.
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2. A fire sensing method comprising the steps of:
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detecting hydrocarbon gas which is produced at a very early state of fire before ignition; outputting a pre-alarm signal upon detection of said hydrocarbon gas indicating a possible fire condition; detecting a second gas which is produced after fire ignition; detecting one of a significant increase and significant decrease in said second gas after detection of said hydrocarbon indicating a fire condition; and outputting a signal indicating detection of a fire only when both said hydrocarbon gas is detected and said one of an increase and decrease is detected in said second gas. - View Dependent Claims (3, 4, 5)
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6. A fire sensing method comprising the steps of:
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detecting hydrocarbon gas which is produced at a very early state of fire before ignition; detecting at least one of radiated heat and temperature; and generating a signal to indicate the detection of fire only when said hydrocarbon gas has been detected and when said at least one of said radiated heat and temperature is detected after detection of said hydrocarbon gas. - View Dependent Claims (7, 8)
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9. A fire sensing method comprising the steps of:
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detecting hydrocarbon gas at a very early state of a fire before ignition; detecting a second gas which is produced after fire ignition; detecting one of an increase and decrease in amount of said second gas; and generating a signal to indicate detection of a fire only when both said hydrocarbon gas is detected and said one of an increase and decrease in said second gas is detected. - View Dependent Claims (10)
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11. A fire sensing method comprising the step of:
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determining whether hydrocarbon gas is present in a monitored region; detecting at least a first gas and a second gas producing during a combustion process; detecting an increase in both said first gas and said second gas; and generating an alarm when an increase in both said first gas and said second gas is detected.
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12. A fire sensor comprising:
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a hydrocarbon gas sensor for detecting hydrocarbon gas produced before ignition; a combustion gas sensor for detecting gases produced during a combustion process caused by said fire; a fire judgment section for detecting the occurrence of a fire based upon whether said hydrogen gas is detected and whether said gases produced said combustion process are detected; and a pre-alarm judgment section, coupled to said sensor, for outputting a pre-alarm signal to said fire judgment section and to an alerting device in response to detection of said hydrocarbon gas which represents an initial stage of a fire; said fire judgment section judging said fire from one of an increase and decrease of said gases detected by said combustion gas sensor only after said pre-alarm judgement section receives a signal from said hydrocarbon gas sensor indicating detection of hydrocarbon gas and outputting a fire alarm signal. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19)
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20. A combination fire sensor comprising:
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a CO2 sensor for detecting CO2 gas produced at a fire; a CO sensor for detecting CO gas produced at said fire; and a comparison section for giving an alarm by judging said fire when a content of said CO2 gas detected by said CO2 sensor has been increased over a predetermined threshold and when a content of said CO gas detected by said CO sensor has been increased above a predetermined threshold. - View Dependent Claims (21)
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22. A fire sensor comprising:
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first means for detecting a hydrocarbon gas and generating a first output signal; second means for detecting the presence of a fire and generating a second output signal; third means responsive to at least said second signal for generating a fire alarm, said third means being responsive to the presence of said first signal for setting a first threshold alarm condition for said second output signal, said first threshold alarm condition being more sensitive than a second threshold alarm condition for said second signal alone.
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Specification