The PTIR Multi-Criteria Smoke Detector by System Sensor are analogue addressable PTIR Multi-Criteria dmoke detector combines three sensing elements into one unit, that are photoelectric sensor for monitoring smoke, thermal sensor for measuring temperature, IR sensor for measuring ambient light levels and flame signatures. The integration of continual monitoring for all three major elements of a fire enables the device to respond far more quickly to an actual fire and has the highest immunity to nuisances. Based upon the sensor signals, the program dynamically changes sensor thresholds, sensor gain, time delays, combination, sampling rates and averaging rates.