System Sensor D4120W Watertight 4-Wire Photoelectric Duct Smoke Detector is designed for reliable smoke detection in HVAC duct systems exposed to harsh indoor and outdoor environments. Its NEMA 4-rated enclosure and low-flow sensing technology ensure accurate performance while simplifying installation, testing, and maintenance.

• NEMA 4 watertight enclosure rated for protection against rain, dust, windblown debris, and hose-directed water
• 4-wire photoelectric duct smoke detector with integrated low-flow technology for HVAC applications
• Operates in airflow speeds from 100 to 4,000 FPM and temperatures from –4°F to 158°F
• Plug-in sensor head provides strong false alarm immunity and simplified maintenance
• Flexible pivoting housing supports square, rectangular, and round duct mounting configurations