System Sensor DUCTSD — 4-wire photoelectric low-flow duct smoke detector.
Duct detectors shut down air handling on smoke detection so the HVAC system does not spread smoke through the building. This one covers the low-velocity end of that job, and its housing pivots between square and rectangular footprints to fit tight clearances. Up to 30 units interconnect for multi-fan shutdown; all transfer their relays, but only the one that saw smoke goes into alarm.
- 4-wire only — not for 2-wire applications; uses the 2D51 plug-in photoelectric head
- 24 VAC/VDC (20–29 VDC) or 120 VAC 50/60 Hz
- 100 to 4,000 ft/min; -4°F to 158°F; 0 to 95% RH
- Alarm initiation SPST 2.0 A at 30 VDC; auxiliary DPDT 10 A; supervisory SPDT
- Housing listed to UL 268A
No sampling tube is included; order one to suit the duct: DST1 (to 1 ft), DST1.5 (1–2 ft), DST3 (2–4 ft), DST5 (4–8 ft), DST10 (8–12 ft). It must span at least two-thirds of the duct width. Never land the auxiliary contacts on a panel initiating circuit.
