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System Sensor 2D51, Low-Profile, 4-Wire Plug-In Detector for Special Applications
Base not included

System Sensor 2D51, Low-Profile, 4-Wire Plug-In Detector for Special Applications

Manufacturer:System Sensor
Manufacturer Part#:2D51
Our Part#:BK-2D51
Stock Status: In Stock
Retail Price:$91.29
Your Savings:$23.74(26%)
Your Price:$67.55


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

Features for 2D51/B210LP/D4P120

  • Low-profile smoke detector design
  • Low standby current
  • Two LEDs blink in standby
  • Detector head plugs easily into base
  • Built-in test switch
  • Field sensitivity metering of detector to meet the requirements of NFPA 72 with the use of RTS2/RTS2-AOS and SENS-RDR
  • Designed for mounting on a standard electrical box
  • SEMS screws for easy wiring and positive wire retention
  • Removable cover and insect screen for field cleaning
  • Remote push button Test/Reset, LEDs provide visual indications
  • Onboard supervisory and alarm relays
  • Accepts 24 or 120V supply voltage
  • Interconnect up to 100 units for common functions
  • Compatible for interconnection with System Sensor InnoviarFlex™ D4120 or D4120W duct smoke detectors and remote accessories


The 2D51 is the HEAD ONLY. The following are compatible with the 2D51:
  • B210LP Base
  • D4P120 4-Wire P/E Power Board
  • RTS151 Remote Test Station
  • RTS151KEY Same as Above, with Key Lock
  • APA151 Remote Annunciator with Piezo alarm
  • RTS2-AOL Multi-signaling accessory
  • RA100Z Remote Annunciator alarm LED
  • MHW mini horn
  • AOS - add-on strobe

The 2D51 can be used as a pendant mount detector in no-flow/low-flow air-handling systems (0-4,000 FPM). The pendant /plenum mounted 2D51 is to be installed into a B210LP base and wired to a D4P120 power board-only control unit. The D4P120 power board is capable of controlling up to two 2D51 sensors.

Pendant mounted in a standard electrical box within the duct, the twist-in/twist-out head allows easy removal from the base for quick cleaning and maintenance. The 2D51 heads can be locally tested using a magnet or by using the test/reset push button on the D4P120 power board.

Remote testing is accomplished using the RTS151, RTS151KEY, RTS-2 or RTS-AOS accessories connected to the D4P120 power board.

The APA151, RTS2 and RTS2-AOS Remote Annunciators with Piezo Alarm can also be connected to the D4P120 power board to provide an audible and visible indication of smoke detector status.


Operating Temperature Range: -4°F to 158°F (-20°C to 70°C)
Operating Humidity Range: 10% to 95% non-condensing
Air Duct Velocity: 0 to 4000 fpm
Dimensions: 2.00"H x 4.1" Diameter
Shipping Weight: 3.1 oz. (88 g)
Voltage Range: See B210LP base specifications
Alarm Current: See base specifications
The System Sensor 2D51 low-profile photoelectric smoke detector with a B210LP base tied to the D4P120 is listed to Underwriters Laboratories 268A specifically for use in no-flow/low-flow air-handling systems.
Accessories designed for use with this product - To add any of these accessories to your order, simply fill in the quantity you want and click the large "Add to Cart" button above
System Sensor APA151, Piezo Annunciator
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System Sensor MHW, 12/24VDC Mini Horn, White
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System Sensor RA-100Z Remote Annunciator
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System Sensor RTS151 Remote Test Station
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