Early detection of fire is critical. Advances in smoke detection has saved lives and continues to do so as detection technology continues to evolve. Aspirating Smoke Detection (ASD) is one of these means of detection that can buy precious seconds for first responders to arrive and occupants to evacuate a building. ASD systems work differently than standard smoke detection and may be the ideal means of detection for your building.

What is Aspirating Smoke Detection (ASD)?

 ASD systems detect smoke before it’s visible to the naked eye. To do this, the system draws air in through a network of pipes that continuously filters the air of contaminants and dust as it seeks to detect smoke or any by-product of combustion. Many of these systems involve multiple levels of detection and can be programmed to be highly sensitive depending on the application.

Early warning thresholds can be set to provide early notification of possible fire or toxic gas conditions. As these additional thresholds are crossed, alarms can be configured to sound, the fire department can be notified, and the pre-action sprinkler valves or gaseous fire suppression systems can be activated.

VESDA, by Xtralis (the inventors of ASD), is one of the leaders in early warning smoke detector systems. VESDA aspirating smoke detection solutions with continuous air sampling provide the earliest possible warning of an impending fire hazard. VESDA aspirating smoke detectors buy the critical time needed to investigate an alarm and initiate an appropriate response to prevent injury, property damage, or business disruption. VESDA detectors have multi-level warnings and a wide range of sensitivity that does not degrade or change over time, so even minute levels of smoke can be detected before a fire has time to escalate.

Basics of an ASD system

The basic ASD system has three main components:

  • The sampling pipe network, which collects air through sampling holes and transports it from the protected space to the detector, where it’s tested for the presence of smoke particulate.
  • An aspirating smoke detector constituted of:
    • A sensing chamber with a high sensitivity sensor to detect smoke particles suspended in air
    • An aspirator or fan to draw air from the protected area to the sensing chamber
    • An optional filter to remove all large particles that may damage the sensor within the sensing chamber
  • The exhaust pipe to expel the sampled air from the detector.

aspirating smoke detection 

While all ASD systems contain similar equipment, the detector technology type varies.

Active vs. passive detection

 Aspirating smoke detection is a form of “active” detection. This is in contrast to traditional smoke detectors that use “passive” detection.

Traditional smoke detectors are “passive” meaning that smoke much reach a detector before the fire alarm system is triggered. “Active” detection on the other hand involves air samples constantly being pulled from a room. Active detectors like ASD systems are incredibly sensitive and able to detect smoke much earlier than passive smoke detectors.

Both systems sound an alarm or activate the building’s fire alarm system when fire is detected. During this time, the fire alarm system will then initiate other actions such as closing fire doors.


 ASD systems can be used in a wide range of industries and applications. Buildings with critical data or very high ceilings are ideal candidates for this type of advanced, early detection.

Most manufactures of ASD systems offer a range of options that are dependent on the size of your building and hazard type.

A benefit of ASD systems is its discrete design, which is another appealing characteristic for some applications. An article detailing today’s advanced fire detection options, published on Facilities.net, explains:

“Due to its design, ASD allows for placement where conventional detection cannot be used, such as historical buildings where a spot detector would disrupt the aesthetics of the building. It is also widely used in harsh environments such as zoo cages or in areas that are difficult for inspections, testing, and maintenance, such as buildings with high ceilings or large atriums. Since ASD can detect the earliest stages of a fire event initiating a pre-alarm condition allowing personnel time to investigate the situation before escalation.”

NFPA requirements for ASD systems

Smoke detectors are just one part of your building’s fire alarm system. These devices are a critical component of the overall fire alarm system. NFPA 101 Life Safety Code outlines the different requirements for the components of a fire alarm system, called “initiation,” “occupant notification,” and “emergency forces notification.”

The requirements for the ASD system are outlined in the Initiating Devices Section of NFPA 72, but NFPA 76 “Fire Protection of Telecommunication Facilities” outlines specifics for Very Early Warning Fire Detection (VEWFD) Systems and Early Warning Fire Detection (EWFD) Systems.

A few of these requirements include a maximum transport time of 90 seconds and minimum alarm sensitivity for a single sampling hold to be a max of 1.5% obs/ft. NFPA also dictates the size of the sampling area. For these systems, the coverage area for a single sampling hole is limited to 400 square feet.

Requirements of VEWFD ASD systems (like the VESDA detectors) are slightly different and include a smaller coverage area limited to 200 square feet, a minimum alert sensitivity for a sampling hole of a maximum of 0.2% obs/ft., and maximum transport time of 60 seconds. There are also requirements for levels of detection.

Hiring a fire protection professional

Fire Systems, Inc. is a leader in the fire protection industry. Our decades of knowledge in fire protection make us a critical resource for local Atlanta businesses. We can design, install, maintain, and repair all aspects of your building’s fire protection system. From sprinkler to suppression, we do it all. If you’re looking for the latest in advanced fire detection, our team of experienced technicians can assist you in finding the best solution for your industry and overall needs as a business. Work with a fire protection company that is knowledgeable in the most up to date fire code for your area. Contact Fire Systems, Inc. today at 770-333-7979 or visit our website for more information.