The 713/7139 Series provides the temporal 3 evacuation tone as a standard feature. When testing the 713/7139 Series it may take up to 16 seconds longer to go in or out of alarm. The smoke alarm operates on the light scattering principle, a superior method of detection in smoldering fires, utilizing a pulsing LED light source and a photodiode sensor in a fully screened sensing chamber. Every 4 to 5 seconds the pulsing LED emits an infrared beam that by passes the photodiode under normal conditions.

However, when smoke enters the sensing chamber, the infrared beam is deflected onto the sensor by the smoke particles. The LED pulse rate increases to 8 times the normal rate, and after the photodiode confirms that smoke is present for 2 consecutive pulses, it will produce the signal necessary to trip an alarm.

Upon activation, the alarm will emit a 90dBA local audible signal and activate the high intensity strobe. During the alarm period the strobe will flash at a brightness of 177 Candela 60 times per minute. After the smoke has cleared from the detector, the unit will revert to the normal stand-by condition.