Conventional Duct Detectors

4-Wire Duct Detectors

Product Overview

The InnovairFlex™4-Wire Photoelectric Duct Smoke Detector D4120 features a pivoting housing that fits both square and rectangular footprints and mounts to round or rectangular ductwork. This unit senses smoke in the most challenging conditions, operating in airflow speeds of 0.5 to 20.32 m/sec, temperatures of -20 °C to 70 °C,  and a humidity range of 0 % to 95 % (non-condensing). A plug-in sensor head offers improved false alarm immunity and simple installation, testing and maintenance. An improved cover design isolates the sensor head from the low-flow feature for simple maintenance.

The InnovairFlex™ housing provides ample wiring space, a 20 mm conduit knockout, and built-in short circuit protection to prevent damage to sensitive components during installation. High contrast terminal designations make wiring easy. With its 2:1 sensor-to-power capability, the power board of the D4120 may be used to monitor a second sensor, D4S simultaneously (i.e. supply and return side). As many as fifty InnovairFlex™ detectors can be interconnected. When one unit senses smoke, all interconnected detectors will switch will switch their relays; only the detector sensing smoke will go into alarm, thus pinpointing the fire source.

An easy-access Test/Reset button makes it possible to test the unit with the cover on. Three DIP switches can be used to configure field selectable settings: cover tamper delay, number of sensors to be controlled, and shut down on trouble option. Each power board has two LEDs that can be used to indicate the status of connected sensors, and a quick reference imprinted on the cover explains the LED status indications (Standby, Maintenance, Trouble, and Alarm). The InnovairFlex™ product line is compatible with all previous Innovair models, including remote test accessories.


  • 4-Wire photoelectric, integrated Low-Flow technology
  • Versatile mounting options: square or rectangular configuration
  • Plug-in sensor offers superb false alarm immunity and the latest sensor technology
  • Patented sampling tube installs from front or back of the detector with no tools required
  • 20 mm conduit knockout
  • One easy-access Test/Reset button and improved LED status
  • Patented interconnect feature for multi-fan shutdown
  • New high contrast terminal designations
  • Built-in short circuit protection from operator wiring errors
  • Field selectable settings for configuring the detector
  • Two DPDT / Form-C relay contacts
  • 24 Vac / dc or 120 Vac
  • Backward compatible with existing Innovair products, including remote accessories

Click here to download the white paper: Duct Application Smoke Detectors

Ordering Information

Product Code



Conv 4 Wire Photo Duct Detector 24VAC/DC &120VAC w/relay No Tube