| 摘要 |
PROBLEM TO BE SOLVED: To provide a differential heat sensor capable of stably operating an electronic contact without being affected by any fine particle under an environment where there is many floating dusts. SOLUTION: This differential heat sensor 1 is provided with an air chamber 2 having a diaphragm 3 on one face and an air hole 4 for blowing inside air to the outside, and when the air chamber 2 is rapidly expanded due to the heat of a fire, the diaphragm 3 is displaced, and brought into contact with an electric contact 7. The air chamber 2 is disposed in parallel with a sub-air tight chamber 6 communicating through the air hole 4 with the air chamber 2 so as to turned to be an air-tight chamber 2, and the sub-air tight chamber 6 is constituted so as to be made expandable according to air blow from the air-tight chamber 2, and so as not to be made expandable according to air blow from the air-tight chamber 2 due to the heat of a fire before the diaphragm 3 is displaced.
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