| 摘要 |
A device for detecting the outbreak of a fire in say, a mine, comprising a housing through which products of combustion can pass. A lamp and a light detector are located on opposite sides of the housing so that light rays are transmitted through the housing to the detector. An interference filter is located between the lamp and the light detector and is designed to pass only light rays having a wave-length corresponding to one of the characteristic wave-lengths of a selected gaseous combustion product such as carbon dioxide. When the combustion product enters the housing energy passes from the light rays to the combustion product and the intensity of the light rays impinging on the light detector thus decreases. This decrease is detected to energize an alarm or the like. |
