Duct Smoke Detector Location Requirements

Return air smoke detectors are not required when there is a protection of.

Duct smoke detector location requirements.

Ventilation fan systems used to remove air from the inside of the building to the outside of the building. One device address is required. Nfpa 90a requires the first duct smoke detector to be installed on the supply side of air handler units of more than 2 000 cubic feet per minute cfm and requires one on the return side of units of more than 15 000 cfm and serving more than one story. Per nfpa 72 detectors should be at least six duct widths down.

When a sufficient amount of smoke is detected in the sensing chamber the duct smoke detector notifies the fire alarm control panel. The duct detector should when possible be located a minimum of six. Codes to determine where smoke detectors are required. Installation instructions for duct smoke detectors mounted on combination fire smoke or smoke dampers ii detector 04 12 to avoid stratification detector placement should be such that there is a uniform airflow through the duct.

Due to smoke dilution in the ducts the duct detectors will respond more slowly than an area detector. In the areas where smoke detectors become inaccessible designers should include smoke detection controls remote from the inaccessible area. Duct smoke detector maintenance requirements are not included in the nfpa standard that covers hvac systems nfpa 90a or 90b. Duct smoke detection nfpa 90a code requirements there are exceptions to the two basic requirements.

Duct smoke detectors should be located in the hvac area between 6 and 10 duct equivalent diameters of straight uninterrupted run. However the international code council s 2015 mechanical code does. The device address is set using the two rotary switches located on the front of the unit. The international mechanical code section 606 2 2 also states that unless multiple air han dling systems share common supply or return air ducts or plenums duct detection is not required in the supply air system.

Designers should also remain aware that duct detectors may not substitute for area smoke detection. The detector is capable of performing comprehensive self diagnostics and storing the results. If the duct system is designed to carry more than 15000 cfm of air you need one in the return and one in the supply.