Airflow measurement for ventilation control in road tunnels

Airflow measurement systems TMS 3000 are specifically designed for working under conditions prevailing in road tunnels. In the driving area there are only robust mechanical sensors made of stainless steel, the evaluation electronics is located in a separate control room (Version A and B).

The high-resolution measurement allows continuous blower control and thus an effective optimization of fans and power consumtion.Our devices have been successfully used in the longest tunnels (e.g. the St.Gotthard Tunnel in Switzerland or Plabutsch in Austria) or shorter tunnels (e.g. University Tunnel in Düsseldorf, Germany).

Measurement is based on high-precision differential pressure measure­ment (Pitot tubes) which results in accurate flow measurement of the air through the tunnel. The data from the separately mounted field transmitters are transferred digitally into the evaluation unit (RS 485).

  • Robust sensor mechanism without moving parts
  • Practically maintenance-free
  • Compact or field transmitter version
  • Measurement in longitudinal direction of tunnels
  • Continuous blower control is possible

Ventilation control in road tunnels - Bauform A, B und C

For new tunnels or for retrofitting this system provides essential advantages:

  • Optimal fit to tunnel geometry due to field transmitter version.
  • Robust sensors made of stainless steel.
  • No moving parts.
  • In the driving area there are no active electronic components (at version A and B).
  • Excellent measurement is still guaranteed even in case of fire (at version A and B).
  • The measuring system is practically maintenance-free (recommended inspection interval 5 years).
  • High resolution of less than 0.1 m/s in both flow directions.
  • Calibration by our accredited test rig installation for airflow (ISO 17025).
  • Information on flow rate through the tunnel cross-section gives precise flow measurement without any impact of road traffic.
  • An absolute zero-point stability thanks to autozero method (automatically recurring “reset” of differential pressure measuring cells).
  • Air pressure measurement is already included.
  • The Pitot tube sensors protrude only for approx. 40 cm into the driving area.
  • The easiest dismounting of the Pitot tubes without tools during recurring cleaning of the tunnel walls.

Important Technical Data: - TMS3000

Measurement of the flow rate through the tunnel (in the longitudinal direction)

2 Pitot tubes for differential pressure per measuring point, mounted on opposite tunnel walls

Measuring ranges: -10 ... 0 ... +10 m/s
-15 ... 0 ... +15 m/s
-20 ... 0 ... +20 m/s
Accuracy < 0,1 m/s
Outputs 4 ... 20 mA for the parameters:
  • Flow rate at the Pitot tube A incl. polarity
  • Flow rate at the Pitot tube B incl. polarity
  • Average value of the flow rate (averaging over tunnel cross-section) incl. polarity
  • Air temperature at the measuring point (-30 … +140 °C, optionally 30 ... +600 °C)
  • Barometer pressure at the measuring point (600 ... 1100 mbar)
  • Status signals
Control input: Reduction of the averaging interval in case of accident