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System Sensor Innovair D4120, 4-wire P/E Low-Flow Duct Smoke Detector
System Sensor Innovair D4120, 4-wire P/E Low-Flow Duct Smoke Detector

System Sensor Innovair D4120, 4-wire P/E Low-Flow Duct Smoke Detector

Manufacturer:System Sensor
Manufacturer Part#:BK-D4120
Our Part#:D4120
Stock Status: Call for Availability
Retail Price:$507.67
Your Savings:$177.69(35%)
Your Price:$329.98


System Sensor







Feature 5


Feature 7

Product Type:Duct Detector|Input Voltage:24VDC,120VAC,Other|Detection Type:Photoelectric|Connection Type:Hardwired,System|Intended Use:Commercial/Industrial|Interconnect:No

The System Sensor D4120 is a direct replacement for the discontinued DH100ACDCLP, DH100ACDCI, DH400ACDCP and DH400ACDCIHT


  • Photoelectric, integrated low-flow technology
  • Air velocity rating from 100 ft/min to 4,000 ft/min (0.5 m/s to 20.32 m/sec)
  • Versatile mounting options in square or rectangular configuration with modular construction
  • Plug-in sensor offers superb false alarm immunity with the latest sensor technology
  • Increased wiring space with a newly added 3/4-inch conduit knock out
  • Broad range for operating temperature (-4°F to 158°F) and humidity (0% to 95% non-condensing)
  • Patented sampling tube installs from front or back of the detector with no tools required
  • 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 120VAC
  • Backward compatibility with existing Innovair products, including remote accessories


The InnovairFlex D4120 4-wire photoelectric duct smoke detector 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 100 to 4,000 feet per minute, temperatures of 4°F to 158°F, and a humidity range of 0 to 95 percent (noncondensing). 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™ Series are the only duct smoke detectors flexible enough to fit configurations from square to rectangular and everything in between.

The InnovairFlex housing provides ample wiring space, a 3/4-inch 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 50 InnovairFlex detectors can be interconnected. When one unit senses smoke, all interconnected detectors 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 duct smoke detector can be customized to meet local codes and specifications without additional wiring. The new InnovairFlex product line is compatible with all previous Innovair models, including remote test accessories.

WARNING: Duct smoke detectors have specific limitations.


NOT a substitute for an open area smoke detector,
NOT a substitute for early warning detection, and
NOT a replacement for a buildings regular fire detection system.

Refer to NFPA 72 and 90A for additional duct smoke detector application information.

Physical Specifications

(Rectangular) - 14.38 in (37 cm) Length; 5 in (12.7 cm) Width; 2.5 in (6.36 cm) Depth
(Square) - 7.75 in (19.7 cm) Length; 9 in (22.9 cm) Width; 2.5 in (6.35 cm) Depth

Weight: 2.5 lb (1.14 kg)

Operating Temperature Range: D4120 & D4S: -4°F to 158°F (-20°C to 70°C); D4P120: -40° to 158°F (-40° to 70°C)

Storage Temperature Range: D4120 & D4S: 22°F to 158°F (30° to 70°C); D4P120: -40° to 158°F (-40° to 70°C)

Operating Humidity Range: 0% to 95% relative humidity non-condensing

Air Duct Velocity: 100 to 4000 ft/min (0.5 to 20.32 m/sec)

View Full Specifications

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