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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

Product 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

Related Products

TunnelTech 305 - Air Flow Monitor
TunnelTech 205 - N02 Monitor

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