The TunnelTech 203 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 203 analyser uses well proven infra-red techniques to determine CO and NO concentrations. As there is only one moving part, reliability levels are very high and maintenance requirements are extremely low.

Key Features

  • Continuous measurement of CO and NO in road and rail tunnels
  • Class leading Accuracy, Repeatability and Resolution
  • Rugged, corrosion resistant construction
  • Minimal maintenance requirements
  • Optional RS 485 (Modbus) Output

SpecificationImagesDocumentationProduct Enquiry



Gas Species Options Single or multi-gas measurements available: CO & NO
Measuring units ppm for CO, m-1 or m for visibility
Response Time CO 2mins /  Vis 10s – 2min Selectable
Ambient Temperature -20°C to +50°C
Power supply 12 – 24V dc 1.5A
Construction Corrosion resistant epoxy coated aluminum housing sealed to IP65
Analogue outputs 3 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 Data For local connection to laptop PC using RS232 or optional RS485 interface unit
Lang Filetype Document Size
English TunnelTech 203 Datasheet 400kb

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