ASPIRATING SMOKE DETECTION – ASD
The detection principle and detection performance of the newest Aspirating Smoke Detection (ASD) technology is presented in this paper.
The optical dual wavelength technology which uses blue and infrared light shows a huge advantage in detection speed and reduction of false alarms compared to other smoke detection technologies.
The detection chamber of the ASD system is especially designed to be very sensitive to little amount of smoke.
Using a shorter wavelength like blue light enables the detection of very small particles which are often present during flaming fires and in the incipient fire state. A combination of blue and infrared light scattering allows discrimination of smoke and dust particles by analyzing its particle size.
Even in harsh environments with a high dust load an alarm will only occur when small particles are created.
Additionally, a venturi bypass is used to minimize soiling of the ASD chamber.
Only a small portion of the overall air stream is passed into the detection chamber.
In the detection chamber minimal soiling is assured by an optimized chamber flow so that smoke and dust particles do not remain in the chamber.
To assure reliable smoke detection the airflow in the pipe is continuously monitored.