SYSTEM SENSOR DST3 Duct Smoke Detector

System Sensor DST3 — metal air sampling tube for duct smoke detector housings, for outside duct widths of 2 ft to 4 ft (0.6 to 1.2 m).

A duct smoke detector draws its sample through an intake tube reaching across the duct, and that tube is not in the detector carton. It is ordered to suit the duct, sized by duct width and not by detector model, because a tube stopping short of the airstream cannot sample it properly.

• Duct widths 2 ft to 4 ft (0.6 to 1.2 m), worded identically by System Sensor, Notifier and Gamewell-FCI
• Must extend at least two-thirds of the way across the duct width
• Inlet holes face into the airflow; the connector arrow has to point upstream
• Trim so about 1 to 2 in. protrudes; use a shorter tube if over two inlet holes fall outside
• The end cap sealing the far end ships with the detector, not the tube, and is called critical to correct airflow

The family is sized the same way: DST1 up to 1 ft, DST1.5 for 1 to 2 ft, DST5 for 4 to 8 ft, two-piece DST10 for 8 to 12 ft. Do not confuse it with ETX, the 1 ft metal exhaust tube fitted downstream, or P48-21-00, the end cap.