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Addressable Optical Smoke Beam Detector


The MI-LPB2 is an addressable reflector- type linear optical beam smoke detector, designed to operate as a component of an intelligent fire alarm system. It operates primarily on the principle of light obscuration utilising an Infra-Red beam. Optical beam smoke detectors are particularly appropriate for protecting buildings with large open spaces such as warehouses, atriums etc. The MI-LPB2 detector is a combined transmitter/receiver unit that can be directly connected to an analogue loop circuit. The Infra-Red transmitter generates a beam of light towards a high efficiency reflector. The reflector returns the beam to the receiver where an analysis of the received signal is made. The change in the strength of the received signal is used to determine the alarm condition. Alignment of the detector is simplified with the aid of the detector’s "gunsight" targeting device. Alignment of the detector with the reflector can then be “fine tuned” with the aid of a numerical signal strength indicator.

Product Overview

The sensitivity of the detector can be set to between 25% and 50% obscuration, providing application flexibility to suit the environment in which the detector will be installed. In addition to the four fixed value alarm thresholds, there are two variable thresholds that automatically compensate for changes in the environment which could otherwise result in unwanted alarms while remaining within a known sensitivity range. The detector incorporates automatic drift compensation, whereby the detector will adjust its detection thresholds in line with any long term signal reduction of the beam caused by contamination of the optical surface. The detector can be adjusted up to 10° vertically and horizontally for alignment. Where greater angular adjustment is required, the multi-mount accessory enables the detector to move through 28° vertically and 360° horizontally when ceiling mounted or up to 23° vertically and 90° horizontally when wall mounted.

Key Features

  • Combined transmitter and receiver unit
  • Range 10-100 metres
  • 4 x fixed sensitivity/threshold levels
  • 2 x automatic variable sensitivity modes
  • Operates in the Infra-Red light spectrum
  • Numerical indicators to aid beam alignment
  • Standby, fault and alarm LED indicators visible from the front and bottom
  • Numerical indicators to aid beam alignment
  • ±10° horizontal and vertical beam alignment
  • Automatic drift compensation
  • Loop powered
  • Complies to EN54-12
  • Extended Warranty


Operating Voltage Range: 15 to 32Vdc (24Vdc nominal)
Typical Standby Current: 2mA @ 24Vdc (No communications, LED off)
Maximum Alarm Current (LED on: 8.5mA
Maximum Alignment Current 20mA


Operating Temperature Range – –30ºC to +55ºC
Humidity 0 to 95% Relative Humidity (noncondensing)
IP Rating IP5


Weight 1.77kg
Max Wire Gauge for Terminals 2.5mm2
Colour: White trim, black box
Material: Bayblend FR110 trim, Lexan lens cover, Noryl backbox
Reflector: 200 x 230mm (10 – 70m range, supplied as standard)


BEAM-LRK Long Range reflector kit (70 – 100m range). 3 off 200 x 230mm.
BEAM-MMK Multi–mount accessory for ceiling or wall mounting with additional mounting adjustment. BEAMSMK also required
BEAM-SMK Surface Mount accessory