Tunnel ventilation systems are designed to enable a sufficient through put of air to be maintained to ensure a safe operating environment for users. These systems consume large amounts of power and need to be operated as efficiently as possible. To do this it is necessary to know the effectiveness of the system in terms of air flow and direction developed within the tunnel. Three decades of development, knowledge and practical experience have been utilised to produce the advanced TunnelTech 801 air flow sensor that combines the reliability of ultrasonic technology and delivers superb accuracy and reliability.

The TunnelTech 801 has been specifically designed for road, rail and civil tunnel and ventilation shaftapplications and represents the latest in compact ultrasonic sensor-head design. Ultrasonic time-of-flight measurement across any tunnel delivers a highly accurate airflow value and virtually eliminates traditional high-maintenance measurement techniques.

Key Features

  • Ultrasonic time-of-flight measurement across any tunnel
  • Real-time accurate measurements of air velocity and volumetric airflow
  • Designed to withstand the harshest of tunnel environments
  • Signal output by analogue/relay or RS 485 MODBUS
  • Extremely low maintenance requirements
  • Class leading Accuracy, Repeatability and Resolution


SpecificationImagesDocumentationProduct Enquiry



Measurements Airflow velocity, Volumetric flow, Airflow direction, Temperature
Measuring units Metric or Imperial units for all parameters
Accuracy ±0.1 m/sec*
Measurement Technique Across the tunnel, dual sensor, ultrasonic transit time principle
Measurement range (typical) -40 to +40 m/sec, range is user configurable
Construction Corrosion resistant IP65 / NEMA 4X enclosure (Kynar® 720)
Outputs / Comminnucation RS485 Modbus, RJ45, 2x 4-20 mA, 2 x Form C SPDT relay,
Ambient Temperature Range -40 to +85°C
Power 24 VDC Power Supply

*depending on calibration, installation, flow profile, temperature and measuring distance

Lang Filetype Document Size
English TunnelTech 801 Series Datasheet 400kb

Download will be instantly be available after form submission.

Send TunnelTech 801 Product Enquiry

Please call to discuss our requirements

Related Tunnel Analysers

TunnelTech 700 Series- Electrochemical CO, NO & NO2 Air Quality Monitor
The TunnelTech 700 Air Quality Monitor, is an essential part of any road or rail tunnel safety system.
View Product
TunnelTech 200 Series - Air Quality
The TunnelTech 200 Series Air Quality Monitors are is an essential part of any road or rail tunnel safety system
View Product