CO / NO / Visibility Stand Alone Gas Monitor for Tunnels

Built with a “stand alone” capability (i.e. it has no need for a control unit), the NOVICOM is a single sensor solution for measuring CO, NO and visibility in road tunnels.  Having been designed specifically for the requirements of tunnel operators, NOVICOM has a low cost of ownership and minimal maintenance requirements.

The NOVICOM tunnel monitor measures the concentration of nitric oxide (NO) and carbon monoxide (CO) in tunnel atmospheres and makes a visible opacity measurement to determine the visibility within the tunnel. These measurements can be used as part of an air quality management system for ventilation control and/or secondary smoke detection within a traffic tunnel or other confined space.

A NOVICOM sensor consists of a Transmitter (TX) and Receiver (RX) mounted “facing” each other on the wall or ceiling of the tunnel. The sensors are located at various points along the length of the tunnel. The distance between the sensors varies depending on national or regional legislation but typically they are installed 250 – 500 m apart.

The TX emits two optical beams, one visible (green) for the visibility measurement and the other infrared (IR) for NO and CO measurement. Both optical beams are received by the RX, where the signals are conditioned and processed on independent internal optical benches.


  • Proven infrared spectroscopy techniques for measurement of nitric oxide (NO) and carbon monoxide (CO)
  • Inferred total oxides of nitrogen (NOX) available from NO measurement, (as authorised by PIARC)
  • Visibility measurement using proven light transmission opacity technique
  • Temperature and humidity compensated measurements to ensure stable readings across all tunnel conditions
  • Choice of interface options enabling easy integration into tunnel control system
  • IP65 / NEMA 4X rated external enclosure supplied with quick release dust protection tubes and wall brackets
  • Supplied complete with PC based utility software for set-up and control of the instrument
  • Optional Operator Interface with display and keypad


  • Designed specifically for monitoring in tunnels
  • Rugged design to withstand corrosive atmosphere and regular tunnel washing
  • Simple installation and alignment
  • Low maintenance requirements
  • Right or left hanging option to enable compliance with regulations governing tunnel light emissions facing on-coming traffic flow
  • Flexible integration options

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