The beam-type smoke detector consists of SPB-24N smoke detectors, which consist of an emitter and receiver. The beam-type smoke detector should be placed where smoke generated by a fire will likely rise and pass through the beam's path. The receiver constantly monitors and measures the intensity of the beam produced by the emitter. Smoke from a fire would cause a decrease in signal strength of a magnitude that exceeds the programmed obscuration setting, generating an alarm signal.