System Sensor 2D51


Low-Profile Photoelectric Plug-in Detector

Availability: In Stock

Condition: New
Brand: System Sensor
Status: Active
SKU: 9896
Manufacturer Part #: 2D51


The 2D51 photoelectronic detector uses a state-of-the-art optical sensing chamber. This detector is designed to provide protection in duct applications when installed with an Innovair Flex 4-wire duct smoke detector housing and to be used with compatible UL listed control panels only.

The 2D51 can also be used in pendant mount applications when installed with a B210LP or B501 base and D4P120 power board components.

Two LEDs on each detector provide local visible alarm indication. They flash every five seconds indicating that power is applied and the detector is working properly. The LEDs latch on in alarm. LEDs will be off when a trouble condition exists indicating that the detector sensitivity is outside the listed limit. See applicable Innovair Flex duct smoke detector installation manual for more information.. The alarm can be reset by a momentary power interruption, test/reset button, or remote test accessory with reset function. This detector may be tested by activating the internal reed switch with a magnet, test/reset button, or remote test accessory.

Additional information

Weight 0.4 lbs
Dimensions 4.10 × 4.10 × 2.00 in









Detectable Medium


Detection Method


Production Status



  • 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


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