The APC In-duct Smoke Detector

Building codes are written and enforced because they protect the public’s most important concerns: health, safety and environment. They also are written to protect efficiencies and investments values. Because commercial HVAC systems can be a source for smoke and toxic gases traveling through the duct system, in-duct smoke detectors have become a code-enforced method for monitoring the dangers. The International Mechanical Code, NFPA 90A: Standard for the Installation of HVAC and NFPA 72: National Fire Alarm and Signaling Code are two such codes that provide critical protection against smoke and toxic gases from the HVAC system from being released into the airflow of a building via the duct system.

Jackson Systems supplies the APC Duct Smoke Detector as a way to alert to early detection of smoke present in the air moving through HVAC ducts in commercial, industrial, and residential applications. The APC Duct Smoke Detector is designed to prevent the recirculation or spread of smoke by air handling systems, fans and blowers.

The APC Duct Smoke Detector continuously “samples” the air in the duct work to ensure it does not exceed safe readings. Should unsafe levels of smoke be measured, the smoke detector shuts down the operations of the system including closing dampers, stopping fans and notifying of the danger.

To monitor levels of smoke in buildings, air sampling tubes are inserted into the duct work. Air sampling tubes come in many sizes and must be properly fitted to their ducts. The sampling tubes must extend between 2/3rds and 80% of the duct width (see illustration). Know that ONE SIZE DOES NOT FIT ALL to meet code. Remember: codes are not just guidelines, they are the law!

The APC Duct Smoke Detector should be connected to the building’s smoke alarm system in accordance with NFPA 72. They work WITH traditional smoke alarm systems and are not intended to REPLACE them. To install, first identify a code compliant location (supply or return side, or both) for the installation of the duct unit that will permit easy access for viewing and serviceability. Note that to minimize the impact of air turbulence and stratification on performance, the APC Duct Smoke Detector should be located as far as possible downstream from any obstruction (i.e. deflector plates, elbows, dampers, etc.). In all situations, confirmation of velocity and pressure differential within specifications is required. After the installation of the duct smoke detector, it is important to have an inspection from Code Enforcement. And, on a regular basis when the building’s traditional smoke alarms are inspected, so should this in-duct system. This keeps your occupants safe and keeps you in compliance with codes.

For more information on the APC Duct Smoke Detector, visit To order, give your Jackson Systems representative a call at 888-652-9663.

Updated: August 1, 2017 — 11:31 pm

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