Early Warning Smoke Detectors

Aspirating Smoke Detector (ASD) is a system used in active fire protection and can typically detect smoke before it is visible to the naked eye. ASD design corrects shortcomings of conventional smoke detectors. These smoke detectors buy the critical time needed to investigate an alarm and initiate an appropriate response to prevent injury, property damage or business disruption. Due to fast response of this type of smoke detection, it calls as Early Warning Smoke Detector (EWSD) or Very Early Smoke Detection Apparatus (VESDA).

In an aspirated detection system, air is sampled from the protected area through a network of pipes or tubes, actively drawing the air towards the detection system using a high pressure aspirator fan to provide the earliest possible warning of an impending fire hazard.

The air samples are captured and filtered, removing any contaminants or dust to avoid false alarms and then processed by a centralized, highly sensitive laser detection unit. If smoke is detected, the systems alarm is triggered, and signals are then processed through centralized monitoring stations within a few seconds.


Typical Smoke Detector Obscuration can be concluded as below:

Detector type Obscuration
Ionization Smoke Detector 2.6–5.0% obs/m
Photoelectric Smoke Detector 0.70–13.0% obs/m
Early Warning Smoke Detector 0.005–20.5% obs/m
Optical Beam Detector 0.06–6.41% obs/m

 Applicable Notes

  • ASD systems incorporate more than one level of alarm.
  • ASD alarm sensitivities are configurable and can be programmed to levels ranging from thousands of times more sensitive than a conventional detector.
  • ASDs are suitable for environments where a highly sensitive rapid smoke detection capability is required. This makes them suitable in clean rooms; areas which contain goods easily damaged by fire, such as tobacco, electronic rooms and highly flammable liquid and gases.
  • To design the pipe network and sampling holes location, please refer to manufacturer’s instructions.

Our Services

SISICO is able to offer an extensive range of Aspirating Smoke Detectors to suit your specific environment from below mentioned companies: