FIRE ALARM

摘要

PROBLEM TO BE SOLVED: To provide a fire alarm more earlier detecting a fire with high accuracy and reducing a false report by integrating and processing signals of sensors detecting an oxygen shortage and the fire.

SOLUTION: This fire alarm has: a fire decision means 2 deciding whether a detection result of the fire sensor 1 exceeds a fire threshold value or not; a fire alarm means 3 issuing an alarm; an oxygen shortage decision means 5 deciding whether a detection result of the oxygen sensor 4 exceeds an oxygen shortage threshold value concentration or not; and an oxygen shortage alarm means 6 issuing an alarm. Both of the oxygen shortage alarm and the fire alarm are issued, so that reliability of the fire detection is improved. The oxygen shortage decision means 5 starts decision of whether the detection result of the oxygen sensor 4 exceeds the oxygen shortage threshold value concentration or not by a provided lower limit threshold value decision means 7 and continuous time decision means 8 when the detection result of the oxygen sensor 4 is present on a higher concentration side than the oxygen shortage threshold value concentration and when a time exceeding a lower limit threshold value concentration set on a lower concentration side than an atmospheric concentration is not more a set time.

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