Codel International Ltd

- Model 201 - CO, NO, Visibility Monitor



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.

As there is only one moving part, reliability levels are very high and maintenance requirements are extremely low. The sight tubes have been designed to ensure that airborne dust and contaminants do not reach the optical windows and cause drift.

Fully configurable analogue and alarm outputs are exportable to the tunnel data acquisition system to provide real-time CO, NO and Visibility data. This data may also be exported via the optional RS485 serial port which delivers MODBUS RTU encoded data to a SCADA system located in the tunnel control centre and/or a local display module. In addition, IP65 rated enclosures are constructed to resist attack from aggressive gases, road salt and the effects of heat.

In areas where extremely low temperatures may be experienced, optional transmitter and receiver insulation jackets are available to reduce the effect.

There are three versions of the TunnelTech AQM available;

  • TunnelTech 201 CO, NO and Visibility monitor
  • TunnelTech 202 CO and Visibility monitor
  • TunnelTech 203 CO and NO monitor
  • TunnelTech 204 Visibility monitor

CODEL’s tunnel sensor range is further extended by additional sensors for the measurement of NO2 and tunnel airflow.

TunnelTech 301 Air Flow Monitor - For the measurement of wind speed and direction

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

  • Gas Species Options: Single or multi-gas measurements available: CO, NO & Visibility
  • Measuring units: ppm for CO & NO, m-1 or m for visibility
  • Response Time: CO 2mins / NO 2mins / Vis 10s – 2min Selectable
  • Ambient Temperature: -20°C to +50°C
  • Power supply: 12V DC @1.5A
  • Construction: Corrosion resistant epoxy coated aluminium 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

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