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 201

CO, NO, Visibility Monitor

The TunnelTech 201 Air Quality Monitor continuously monitors CO, NO & Visibility and is an essential part of any road or rail tunnel safety system.


The TunnelTech 201 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 201 analyser uses well proven infra-red techniques to determine CO and NO concentrations and optical attenuation to monitor visibility levels. As there is only one moving part, reliability levels are very high and maintenance requirements are extremely low.

Features & Benefits

Related Products

TunnelTech 305 - Air Flow Monitor
TunnelTech 205 - N02 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 201 Specification

      Gas Species OptionsMaximum 7 gases from: CO | NO | NO2 |NOx | N2O | SO2 | HCl | CH4 and CO2. Gas temperature pressure and H2O for data normalisation are standard.
      Measuring unitsppm | mg/Nm³ | mg/m³ | %
      Response TimeLess than 200 Seconds (T90)- MCERTS Specification
      Ambient Temperature-20°C to +50°C
      Power supply48V DC from CEMS Control Panel
      ConstructionCorrosion resistant epoxy coated aluminium housing sealed to IP66
      Analogue outputs4-20mA current outputs for each gas channel supplied isolated. 500O load max fully configurable from software
      Logic Outputsup to 8 x volt-free SPCO contacts 50V 1A max. Configurable as alarm contacts | 1 x volt-free SPCO contact 50V 1A max for data valid signal
      Serial DataRS485

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