Worldwide Support
Over 25 distributors and support centres worldwide

Flexible maintenance contracts
Tailor made plant specific contracts with 24Hr Support

30 years experience
Developing, manufacturing and installing


TunnelTech 202

CO, Visibility Monitor

The TunnelTech 202 Air Quality Monitor continuously monitors CO, & Visibility and is an essential part of any road or rail tunnel safety system.


The TunnelTech 202 Air Quality Monitor is an essential part of any road or rail tunnel safety system. Firstly, it monitors the atmosphere within the tunnel and ensures that the tunnel ventilation system provides sufficient clean air to protect tunnel users health and for drivers to clearly see the road ahead.


The TunnelTech 202 analyser uses well proven infra-red techniques to determine CO concentration and optical attenuation to monitor visibility levels. 

Features & Benefits

Related Products

TunnelTech 305 - Air Flow Monitor
TunnelTech 601 - Luminance Monitor

Brochure Download

    Looking for a manual?

    Please contact us below and we will be happy to help you.

    Ask a question

    For further information on any of our products, please complete our enquiry form and a member of staff will respond as soon as possible.

    You can also call: +44(0)1629 814351

      TunnelTech 202 Specification

      Gas Species OptionsSingle or multi-gas measurements available: CO, NO & Visibility
      Measuring Unitsppm for CO & NO, m-1 or m for visibility
      Response TimeCO 2mins / NO 2mins / Vis 10s – 2min Selectable
      Ambient Temperature-20°C to +50°C
      Power Supply12 – 24V dc 1.5A
      ConstructionCorrosion resistant epoxy coated aluminium housing sealed to IP65
      Analogue Outputs3 x 4-20mA current outputs as standard, isolated, 500Ω maximum load, fully configurable
      through TunnelTech software
      Relay Outputs 3 x volt-free SPCO contacts, 50V, 1A max, configurable as alarm contacts
      Serial DataFor local connection to laptop PC using RS232 or optional RS485 interface unit

      For a full product specification please download the product brochure below.