Patent attributes
The present smoke detection system uses a single sensor to quickly detect both fast flaming fires and smoldering fires while further reducing nuisance and false alarms. In the present detector, the sensor is preferably an ionization sensor. Specifically, a first algorithm is used to detect flaming fires and second algorithm is used to detect smoldering fires. An alarm is sounded when either algorithm generates an alarm condition. In each embodiment, the first algorithm generates an alarm condition when a sensor output signal exceeds a first threshold. The alarm condition is generated for the second algorithm when the sensor output signal: (1) exceeds a second threshold for T time.; (2) rate of change exceeds a predetermined rate of change threshold; (3) change between time Tn and time Tn-1 exceeds a predetermined change threshold; or (4) sensor signal exceeds an historic standard deviation of the signal multiplied by a predetermined constant.
