FREMGANGSMAATE OG ANORDNING TIL BRUK VED FORHAANDSDETEKTERING AV BRANN.

摘要

The early warning fire alarm system uses a detector (1) incorporating a temp. sensor (3) responding to temp. variations in the surrounding air which exhibit a frequency variation of between 0.1 and 20 Hz. The detector (1) has at least one further sensor which monitors a different parameter for detection of a fire, e.g. a light dispersion smoke sensor. Pref. the output signals from both sensors (3) are coupled to a logic circuit coupled to an output circuit providing an output signal for indicating a fire alarm, when both sensors (3) simultaneously indicate a fire. The output signals from each sensor (3) may be compared with a respective threshold value. The threshold for the smoke sensor lowered when the threshold value for the temp. sensor (3) is exceded.