| 摘要 |
A pneumatic infrared gas detector includes a pair of expansion chambers and a pair of pressure chambers, each of which is connected at one end thereof to the corresponding expansion chamber. Each of the pressure chambers is divided by a diaphragm into a first chamber connected to a corresponding expansion chamber, and a second chamber, such that the first chamber of one of the pair of pressure chambers is connected to the second chamber of the other of the pressure chambers through a first communication path, and such that the second chamber of the above-indicated one of the pressure chambers is connected to the first chamber of the other of the pressure chambers through a second communication path. A pair of pneumatic pressure detecting elements are provided each of which includes an electret film having one surface on which an electrode is formed, and an electrode plate disposed in opposed relationship with the electret film. The electret film is formed on a first side of a corresponding one of the diaphragms in each pressure chamber, and the electrode plate is supported and fixed at a position that is opposed to a second side of the corresponding diaphragm.
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