How Duct Smoke Detectors Work
Duct smoke detectors can detect if fumes or smoke are present in air handling equipment and if smoke or fumes are detected, they will close the dampers on the duct and will shut down the blowers and fans that circulate oxygen throughout the building. This prevents the fire’s distribution by removing the source of oxygen. In addition, there will be a visible and audible signal sent to the fire control panel.
Duct smoke detectors come outfitted with two alarms: a trouble condition, which can be triggered when there is a malfunction in the power running to the detector, and a fire condition alarm which detects smoke causing the alarm to be triggered. The implementation of these two alarms helps decrease the frequency of false alarms.
Do I Need Duct Smoke Detectors for My Fire Detection System Design?
The requirement for duct smoke detectors with HVAC systems is for airflows that exceed 2,000 cubic feet per minute. This includes commercial buildings that have multiple air handling systems if they share ducts with a combined design capacity that is greater than 2,000 cfm. The location of where duct smoke detectors are installed will depend on the governing codes in your area.
High Rise Security Systems, HRSS, provides fire safety consulting with fire and life safety experts trained in customizing integrated fire safety systems for your commercial building needs. Our experts are trained on National Fire Protection Association (NFPA) code requirements to ensure your commercial fire and life safety system meets all mandated regulations, such as the NFPA 101 Life Safety Code.
Duct smoke detectors should never be a replacement for area smoke detectors. In contrast, they should work together to complete your fire detection system design. Commercial buildings still need area smoke detectors to meet fire safety requirements because if the air-handling unit is not up and running, the duct smoke detector will not be able to detect smoke.
Inspection of Your Commercial Fire Safety Duct Smoke Detectors
Just like the rest of your fire alarm system, duct smoke detectors should be inspected by trained and licensed fire safety experts at least annually, or more depending on your property and business operations. HRSS includes comprehensive commercial fire safety system services which include inspection of your fire safety system to ensure compliance with all federal, state, and local regulations.
HRSS fire and life safety professionals are trained in conducting all required inspections on your duct smoke detectors. These inspections should include:
- Ensuring the smoke detector has no signs of damage, is unobstructed, and is firmly mounted to the duct
- Making sure there are no signs of damage to the circuit board
- Ensuring clear visibility of the control unit trouble signals
- Checking that the in-line filters are clean
- Checking that the sample ports are unobstructed, and the sampling pipe is conspicuously
identified - All sampling system fittings and piping are airtight and firmly fixed
- Checking that the remote annunciators are free of damage and in good operational order
- Ensuring there are no interferences in the smoke detectors vicinity affecting the duct’s airflow
In addition to inspections of your duct smoke detectors, there also must be annual testing and inspections of all fire alarm safety systems. These must be conducted by licensed professionals who are knowledgeable of all code regulations. NFPA Code 72 requires:
- Conducting testing of sampling tubes to ensure the airflow in the ducts will be properly sampled. All tests must adhere to the manufacturer’s recommendation for the specific make and model of the duct smoke detectors being tested.
- Testing to ensure the right pressure differential between the outlet and inlet tubes is within the allowed range as stated by the manufacturer.
- Testing the sensing chamber of the detector to guarantee smoke can physically enter the detector.
When conducting these tests, HRSS’ knowledgeable team of experts will alert the proper authorities to inform them the smoke alarm system is having maintenance and testing performed and will be temporarily out of service to avoid unwanted false alarms.
HRSS is fully equipped with the knowledge and experience to fully customize your integrated commercial fire safety system and perform all necessary testing and maintenance to adhere to NFPA regulations. We offer quality UL-listed fire alarm equipment including duct smoke detectors from the best names in fire safety. Contact our fire safety consultants today for a comprehensive consultation to receive the best commercial fire and life safety system for your needs.