Smoke detecting apparatus for fire alarm

摘要

A smoke detecting apparatus for fire alarm of the present invention has a smoke chamber into which smoke to be detected is introduced, a light emitting lamp disposed in the smoke chamber, a light receiving element disposed in the smoke chamber so as to receive the light emitted from the light emitting lamp, an amplification device for amplifying an output signal from the light receiving element, a detection device for detecting the density of the smoke on the basis of an output signal from the amplification device, a comparison device for comparing the value of the output signal from the amplification device with a fixed value, an abnormality output device for outputting an abnormality indication when the value of the output signal from the amplification device is judged to be smaller than the fixed value by the comparison device, an augmentation command switch for commanding augmentation of the value of the output signal from the amplification device, and an augmentation device for augmenting, in accordance with a command from the augmentation command switch, the value of the output signal of the amplification device which is input to the comparison device.