Gas monitoring in-situ

CO concentrations of over 50 ppm in breathing air lead after a short time lead to impacts well-being, concentration and health. To avoid such impacts by a proper ventilation CO concentration in the tunnel’s driving area is monitored.

The sensor is directly mounted at the measuring point. Air is fed into an electrochemical gas sensor by a capillary. The CO gas reacts at the sensor’s sensing electrode and a current proportional to the gas concentration is generated.

Given this current the sensor calculates the gas concentration and shows it on its display in ppm. The output current depends on the chosen measuring range and the measured gas concentration.

The sensor by a menu guided process can be recalibrated with zero and reference gas such that long time drift can be compensated.

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t/ECS Gas sensor

  • Mounted directly in the tunnel’s driving area
  • Electrochemical sensing of the gas concentration
  • Sensor cells for different gases: CO, NO, NO2 and others
  • Passive, analogue 2-wire transmitter 4-20 mA
  • LCD to display measured value
  • Selectable measuring range
  • Menu guided recalibration with zero and reference gas without the need to open the sensor housing
  • Simulation of output values
  • Available either in wall-mounted or flush-mounted stainless steel housing or with a stainless steel cover if the inner sensor housing is mounted behind an existing panel
  • Protection against splash water and water jets during tunnel wash events


Product info DE (PDF, 340 kB)
Product info EN (PDF, 340 kB)


System setup


Gas sensor t/ECS

The gas sensor is mounted in a height of about 1.5 m above the carriageway.


Visibility sensor VisGuard

The gas sensor t/ECS can be either connected to the visibility sensor VisGuard or directly to the tunnel control system.


Connection to tunnel control system
The gas sensor t/ECS can be directly connected to the tunnel control system through its analogue output. When used together with the visibility sensor VisGuard the system can be connected via analogue outputs or via RS-485 MODBUS RTU.