Smoke Detector

Optical Smoke Detector


  • Smoke detection
  • Relay output
  • Test facility via Magnet
Code: 31940
1 in Stock
Prices Exclude VAT
This part may require a power supply dependent on how it is used, choose from accessories. No cables included.

FDR26 Optical Smoke Detector is designed to detect smoke and signal a fire alarm. If the detector senses smoke, a relay is activated. Since FDR26 does not react to temperature changes, it is suitable for installation in data centers and telco rooms.

Smoke detector with relay output technical overview

An optical smoke detector reacts to smoke that enters the detection chamber and not heat. The detected presence of smoke is indicated by illuminating an LED and switching a relay contact. Smoke is detected only if it directly "hits" the sensor. The alarm condition continues until the detection chamber is free of smoke particles. This product is intended to be used with an external 12V power source - it is not battery powered.

Smoke Detector Images

  • FDR-26 Smoke Detector

Smoke Detector Specifications

Smoke detector installation

When installing the smoke detector, please pay attention to the following guidelines:

  • If the room to be protected is longer than 10 m (30 ft), use two detectors.
  • The best placement is in the center of the ceiling. If the sensor cannot be placed in the center, install it at least 50 cm (2 ft) from the nearest corner of the room.
  • Only install the detector on a wall if it's absolutely impossible to install it on the ceiling. Again, keep the detector at least 50 cm (2 ft) from the corners of the room. This is important for proper smoke detection.
  • The sensor uses only the optical method to detect smoke. Temperature fluctuations do not cause false alarms. This makes the smoke detector very suitable for rooms where there can be temperature fluctuations such as server rooms.

Testing the smoke detector with a magnet

On the top plastic cover, there is a "TEST" label near one of the LEDs. If a magnet is placed near this point, the detector is activated and signals an alarm. This test only tests the electronics and the output relay, the actual smoke detection is not tested.

Connection of smoke detector to SNMP websensors

The relay output of the FDR26 makes it suitable for connecting to Sensormetrix products supporting dry contact inputs. In doing this, activation of the smoke detector can cause emails to be sent, SNMP traps to be triggered, and the smoke detection event to be logged.

No wiring or power supply is provided with the FDR26. A 4-core cable suitable for use with the smoke detector is listed as an accessory below. Some products such as the H3531R and Poseidon 4002 provide a 12V output that can power the FDR26. If a power supply is required, it is suggested that a standard 12V power supply be used and the DC jack cut from it so that the power supply can be directly wired into the FDR26's terminal block. Note: In the event of a fire, power could fail. Unless the smoke detector is connected to an uninterruptable power source, it is not recommended that it be used as a buildings primary source of smoke/fire detection.

The output relay is set at the factory to be Normally Open (NO), but this can be changed to Normally Closed (NC) by removing the back of the unit with a screwdriver and adjusting a link (see instructions that come with the Smoke Detector)

The relay output can be directly connected to a dry contact input. The connections of the FDR26 are

  • (2) +12V
  • (5) GND
  • (6) Relay NO/NC
  • (3) Relay Common

Smoke Detector Specification Summary

Feature Specification
Dimensions 100mm diameter, 45mm high
Power supply voltage 10.5V to 14V
Current consumption 32µA standby, 55mA when in alarm
Start up time 60 seconds (current consumption 80mA)
Protected area 40m2 maximum, 7m maximum height
Maximum air velocity 600m/minute
Testing - electronics Using a magnet
Testing - smoke Test Aerosol
Relay contacts rating 30V, 1A DC (0.5A, 125V AC)
Operating temperature 0°C to 70°C
IP protection IP42
Standards compliance EN54-7:2001

Downloads & Software


  • 4 Core unshielded cable 22AWG 10m length with terminal block
    • 4 Core cable
    • 10m Length with terminal block on one side
    • Suitable for use with Dry Contact Smoke/Fire Detectors and LD-12 Flood sensor
    • 4-Core Connection Cable 10m
      Stock: 0
  • 4 Core unshielded cable 22AWG 5m length with terminal block
    • 4 Core cable
    • 5m length with terminal block on one side
    • Suitable for use with Dry Contact Smoke/Fire Detectors and LD-12 Flood sensor
    • 4-Core Connection Cable 5m
      Stock: 0
  • DC power strip for splitting 12V supplies to power sensors
    • Supports Sensormetrix 12V centre positive power supplies
    • Splits out power supply rails to power sensors
    • DC Power Strip
      Stock: 4
  • 100-240V AC - 2.1mm x 5.5mm x 12mm centre +ve Pin, 15W Multi Region Adapter
    • 12V Multi-region Wall Mount Power Supply
    • 12V DC, 1.25A Output via 2.1 x 5.5 x 12(mm) Straight centre positive jack
    • Interchangeable Input: UK, Europe, US, Australia
    • Power Supply 12V (2.1mm pin)
      Stock: 2
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