AIRFLOW Direction Model for Tunnels

AIRFLOW Direction Model for Tunnels

AIRFLOW offers a rugged, non-contact solution for the universal requirement to monitor air velocity and direction in any tunnel application.  AIRFLOW is a low cost, low maintenance solution that is ideally suited to tunnel environments.  A modern design, using the latest technology and components, housed in a stainless-steel enclosure – this instrument is closest yet to a “fit and forget” airflow monitor.

The AIRFLOW tunnel monitor is a self contained Transceiver (TRX)  designed to be mounted on the tunnel wall. It consists of a square  enclosure base, which is populated with four ultrasound transceivers and  a reflection “roof”, suspended over the ultrasound transceivers.Ultrasound signals are emitted from the transceivers and are bounced off the “roof”. The reflected signals are then received by the transceivers. The time taken for the ultrasound to travel this reflected path is accurately measured and the velocity (and direction) of air can be calculated.

System Components:

  • AIRFLOW sensor
  • PC based utility software package for set-up and control of the instrument
  • Optional Operator Interface with remote or local mounting configurations
  • Optional LSZH cable
  • Optional variable input AC power supply


  • Proven ultrasonic transit time measurement technique
  • Measurement independent of the temperature, pressure and composition
  • of the tunnel atmosphere
  • Single and dual axis models available
  • Optional temperature monitoring facility
  • Choice of interface options enabling easy integration into tunnel control system
  • IP65 / NEMA 4X rated external enclosure
  • Optional Operator Interface with display and keypad


  • Designed specifically for monitoring in tunnels
  • Rugged design to withstand corrosive atmosphere and regular tunnel washing
  • Simple single point installation on one wall, requiring no alignment and no calibration
  • Fixed ultrasonic path length, calibrated when built making it a “fit and forget” monitor
  • No moving parts and no regular service requirement
  • Flexible integration options

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