Duct Smoke Detector Location Requirements

Duct smoke detection nfpa 90a code requirements there are exceptions to the two basic requirements.

Duct smoke detector location requirements.

If a central fire monitoring system is in place a duct smoke detector is in use it must be connected to the fire monitoring system. The device address is set using the two rotary switches located on the front of the unit. Return air smoke detectors are not required when there is a protection of. One device address is required.

Designers should also remain aware that duct detectors may not substitute for area smoke detection. 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. Codes to determine where smoke detectors are required. Duct smoke detectors should be located in the hvac area between 6 and 10 duct equivalent diameters of straight uninterrupted run.

Duct smoke detector maintenance requirements are not included in the nfpa standard that covers hvac systems nfpa 90a or 90b. 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. 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 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. However the international code council s 2015 mechanical code does. The detector is capable of performing comprehensive self diagnostics and storing the results. Due to smoke dilution in the ducts the duct detectors will respond more slowly than an area detector.

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. The duct detector should when possible be located a minimum of six. Detectors should not be mounted in areas of extreme high or low temperatures in areas where high humidity exist or in areas where duct air may contain gases or excess dust.