Visibility Monitors

Flow Monitors


D-FL 220T Ultrasonic flow velocity monitor

Measuring system for continuous evaluation of flow velocity and flow direction in tunnels.

Ultrasonic sensors for tunnel ventilation control system. Reliable measurement across the tunnel profile.

Two identical sensors alternately transmit and receive ultrasonic pulses. The system evaluates the transition times dependant on direction and calculates flow speed. D-FL 220T requires extremely low maintenance.

D-FL 220T

  • stand-alone system, no control unit required
  • simple configuration
  • corrosion resistant against aggressive tunnel atmosphere
  • sensors can be replaced quickly, no tools, no re-alignment required
  • signal transfer
    - per 4-20mA analog signal and 2 relays
    - per RS 485 bus via MODBUS RTU protocol
  • minimized spare requirements
  • extremely low maintenance
  • Applications
  • Technical Data
  • Downloads

    suitable for flow measurement in

  • road tunnels
  • railway tunnels

    provides signals for ventilation control system

  • to monitor the air flow speed
  • to allow control of flow speed in case of fire
D-FL 220T Application data
flow speed, flow rate
flow direction
sample gas air
flow velocity -20 .. 20 / -10 .. 10 / 0 .. 10 / 0 .. 20 m/s
sample gas moisture 0 - 100% relative humidity
ambient temperature -25 to 55 °C
conformity EN 61 326-1 (2006)
EN 61 010-1 (2001)
RABT 2006
ASTRA guideline ventilation of road tunnels - 2008, V2.01
RVS 09.02.22 2007
remarks corrosion resistant against agressive gases, withstands lavation process in tunnels
D-FL 220T Technical data
measuring principle evaluation of transition times of ultrasonic pulses dependant on direction and subsequent calculation of flow speed
measuring path 1.2 - 25 m
orientation of measuring path (0) 30 - 60°C to tunnel axis, typically 45°
measuring range -40 to 40 m/s
any interval can be assigned to analog output
default: 0-20 m/s
response time > 1s … 180s, programmable
resolution 0,1 m/s,
accuracy depends on: installation, path length, flow profile, typ. <+- 0,2m/s bei 3m/s
D-FL 220T M measuring head
ambient temperature -25 to 55°C
MTBF >170.000 h within service life if used within specifications
measurement output 1x 4-20mA, 400 Ohm, isolated, can be assigned by any measured
component and output range
1 x RS 485 Modbus RTU, bi-directional to control room
status output 1x failure, relay NC
1x flow direction, relay NC
max. load: 48V, 0,5A
signal transfer 1x Intercom RS 485 Master-Slave communication
service interface USB 1.1
service software D-ESI 100, requires laptop with Windows XP ™ OS
check cycle internal automated routines, self test
power supply 24 VDC +- 10%, ca. 1 A
protection IP 67
dimensions (h x w x d) 270 x 130 x 95 mm
weight 2,2 kg
material 1.4571/316Ti, polyamide, ca. RAL5017 fire class: B1 (UL 94 V0)
protection D-FL 220T BW Mounting bracket
weight ca. 1,5 kg
material 1.4571 / 316Ti
fixation 4x bolt, od= 8 to 10mm
D-TB 100T A terminal box
ambient temperature -25 to 55°C
power supply 90 - 264 VAC, 48 - 62 Hz, 30 VA includes 24VDC supply for D-FL 220T
dimensions (h x w x d) 9 ca. 160 x 160 x 110 mm
protection IP 66
weight ca. 1,5 kg
material polycarbonate, ca. RAL 7035
fire class: B1 (UL 94 V0)
fixation 4 x bolt od= 8 to 10 mm
remarks * variants
Subject to technical modifications!