t/FL-DP is positioned at two points in a tunnel cross section and measures the longitudinal air flow. The method allows to optionally remove all electronic components from the tunnel’s driving area to maintain a measurement also under high temperatures.
Two differential pressure pitot tubes are mounted on opposite tunnel walls. Measuring the air flow at two points allows to calculate a representative average air flow over the tunnel cross section.
An air flow in the tunnel generates a dynamic pressure on the side of the pitot tube facing the flow of air while on the other side only the static pressure is present. The measured differential pressure is used to calculate the air velocity under consideration of the also measured temperature. The values of the two measuring points are then averaged.
The following outputs are available: air velocity, direction of air flow, air temperature.
Features
- Robust air flow monitoring system based on high-precision differential pressure measurement.
- Two-point mesh.
- Automatic zeroing of differential pressure transducers.
- Touch evaluation and control unit to display measured values, status and set parameters.
- Connection to tunnel control system by RS-485 MODBUS RTU, optionally by analogue outputs and relay contacts.
System
- Two differential pressure pitot tubes mounted on opposite tunnel walls; pneumatically connected to the terminal boxes
- Terminal boxes with differential pressure transducers to be mounted in the tunnel or remotely outside of the driving area (high temperature variant); either
- 1 terminal box: pneumatic connection to opposite side
- 2 terminal boxes: electric connection to opposite side
- Touch evaluation and control unit to be mounted in closet outside the tunnel’s driving area (niche, cross-cut, etc.); Connection to terminal box by RS-485 MODBUS RTU; Connection to tunnel control system by RS-485 MODBUS RTU
- Optional analogue outputs and relay contacts by DIN rail mounted devices
Advantages
- Specifically designed for tunnels
- Easy installation and setup
- Long term stability by automatic zeroing
- Measurement possible at high temperatures
- Corrosion resistant against aggressive tunnel atmosphere
- Minimised spare requirements
- Extremely low maintenance requirements
