D-FL 220

Volume flow measuring system

Suitability tested and certified ultrasonic measuring system to measure the velocity and the volume flow of flue gas or process gas in pipes or ducts, especially for wet and aggressive smoke emissions.


  • Non-contact measuring method
  • Measurement possible below dew point and for high dust concentrations
  • Continuous measurement of normalized volume flow and gas velocity
  • Automatic zero point and reference point control
  • Convenient operation via remote access with web interface
  • Operation with or without control unit
  • Very low maintenance

Your benefit

  • Certified for official emission monitoring
    Type approved according to EN 15267-3, compliant with the requirements of 40 CFR 60 US-EPA PS-6
  • Precise velocity and volume flow monitoring
    Ultrasonic technology allows for precise measurement of flow speed in the complete measuring range
  • Suitable for harsh flue gas conditions
    Non-contact measurement with purge air cushion technology allows for volume flow and velocity monitoring in wet and aggressive flue gases
  • High durability
    No moving parts stand for low maintenance costs and a long lifetime
  • Designed for a wide range of environmental conditions
    Corrosion-free plastic housing with a high IP rating and a broad ambient temperature range
  • Reliable emission monitoring
    Automatic control functions ensure reliable measuring values


Suitable for velocity and volume flow measurement

  • Volume flow measuring at low speeds
  • Plants with damp and/or aggressive exhaust gas
  • Volume flow measurement at high dust content


  • Plants requiring official approval acc. to IED 2010/75/EU
  • Plants requiring compliance to 40 CFR 60 US EPA PS6
  • Emission trading of green house gases GHG acc. to 2003/87/EG / MRR
  • Power industry
  • Biomass incineration
  • Waste incineration
  • Cement industry
  • Crematories
  • Process monitoring

Technical Data

Flue gas typeAir, flue gas, non flammable process gas
Flue gas temperature-40 … 300 °C
Inner stack/duct pressure (relative to ambient pressure)-50 … +20 hPa
Flue gas relative humidity0 … 100 % RH, condensation allowed
Flue gas flow velocity0 … 40 m/s
Stack/duct inner diameter0.5 … 13 m, temperature dependent
Measuring principleMeasurement of direction-dependent transition times of ultrasonic pulses, thereof calculation of flow speed and volume flow
13., 17., 27., 30. BImschV
TA Luft
EN 14181
EN 15267-1, -2, -3
DIN EN 16911-2
40 CFR 60 US EPA PS6
CertificatesCE, QAL1 (DIN EN 14181 / DIN EN ISO 14956 / DIN EN 15267-3), MCERTS, EAC
Measuring locationIn-situ, non-contact. Mounted at stack, measurement across the stack, purged sensors are not in contact with flue gas
Measuring path length1 … 15 m, temperature dependent
Measuring angle45° ±15° relative to the flow direction
Self-check, protective functionsAutomatic internal self-test
Automatic zero- and span check
System componentsD-FL 220 MK measuring device transmitter
D-FL 220 MK messuring device receiver
D-FL 220 SPF purge flange
D-FL 220 E mounting flange with tube (option)
D-ISC 100 universal operating unit (option)
D-TB 100 terminal box (option)
D-BL pure air unit (option)
Physical measuring valueDirection-dependent transition time of ultrasonic pulses
Derived measuring valuesFlow velocity and direction, volume flow at operating conditions or normalized
Measuring range gas velocity0 … 40 m/s
Output range gas velocityFreely programmable
Measuring range volume flow0 … 5000000 Nm3/h
Output range volume flowFreely programmable
Measuring range temperature0 … 400 °C
Output range temperatureFreely programmable
Resolution0.1 m/s
Lowest detection limit0.2 % of the certified measuring range
Combined standard uncertainty
acc. to QAL1, DIN EN 14181
0.34 m/s
Integration time1 … 180 s, freely programmable
Process connectionD-FL 220 E mounting tube with flange, DN80 PN6, tube ID = 100 mm
Digital interfacesRS 485 Modbus RTU, bi-directional communication, USB (Service)
Analog outputs1 x 4 … 20 mA, 400 Ohm, isolated, assignment parameterisable
Digital outputs2 x contact NC/NO, permissible load 60 VDC / 30 VAC / 0.5 A, function can be assigned. Typically: maintenance, failure
Power supplySensor supply voltage 24 VDC ±10 %, 0.5 A
Ambient temperature (operational)-40 … +70 °C
IP protection class (IEC 60529)IP65
Dimensions (HxWxD)Measuring head housing: 113 x 84 x 188 mm (190 x 190 x 330 mm with purge air flange)
Measuring probe (DxL): 110 x 230 … 2270 mm, other on request
Weight6.5 kg (sensor head 610 mm with purge air flange, weight depending on version)
MaterialHousing: Polyamide, RAL 5017,
Ultrasonic transducer: PA6.6, PBT, FRP, both fire class B1 (UL 94 V0),
Process parts: Stainless steel 1.4571 (316 Ti)
Mechanical interfacesPurge air connector OD = 40 mm
Air supply capacity10 … 40 m3/h (per measuring device)
Process connectionDN80 PN6
Dimensions (HxWxD)190 x 200 x 90 mm
Weight2.9 kg
MaterialStainless steel 1.4571 (316 Ti)
Process connectionDN80 PN6
Dimensions (HxWxD)108 x 335 … 2135 mm
Weight5.5 kg (L = 335 mm, depending on version)
MaterialStainless steel 1.4571 (316 Ti)
GFK (Durabest 180)
Power supply90...264 VAC, 48...62 Hz
Power consumption200 VA
Ambient temperature (operational)-40…+60 °C
IP protection class (IEC 60529)IP65
Dimensions (HxWxD)230 x 200 x 111 mm
Weight4 kg
MaterialAluminum, painted
Mechanical interfaces2 x purge air connector OD = 40 mm
Power supply115 / 230 VAC, 50 / 60 Hz
Power consumption0.37 kW (50 Hz) / 0.43 kW (60 Hz)
Air supply capacity40 m3/h (50 hPa) / 60 m3/h (25 hPa)
Ambient temperature (operational)-20 … +50 °C
IP protection class (IEC 60529)IP55
Dimensions (HxWxD)480 x 450 x 320 mm
Weight12 kg
MaterialStainless steel 1.4301

The universal operating unit D-ISC 100 can be connected to several DURAG sensors. It allows parameterization and maintenance of all connected sensors via the integrated keypad or a connected PC and also supports remote access via intranet or internet connection.

 Opens internal link in new window-ISC 100

  • The suitability of the D-FL 220 for the listed ranges, especially the max. measuring length depends on the sample gas temperature, the dust type and it's size distribution.
  • Subject to technical modifications.


Universal display and operating units

The universal operating unit  Opens internal link in new windowD-ISC 100 allows the connection of several DURAG devices. It allows parameterisation and maintenance of all connected devices via integrated keypad or a connected PC and also supports remote access via intranet or internet connection.


Our  Opens internal link in new windowD-ESI Service and Parameterisation Software  assists you to manage all your DURAG sensors connected in one network system via a uniform graphical Interface.


Please contact your sales representitive for more Information.

Supply unit

  • Opens internal link in new window D-TB x00 in various versions
  • for voltage supply of one DURAG sensor
  • different housings available
  • version with integrated purge air blower available

Please contact your sales representitive for more information.

Purge air blower

  • D-BL xx in various versions
  • for supplying the measuring head with purge air
  • weather protection cover available as an option

Please contact your sales representitive for more information.

We offer various accessories such as weather protection covers for your sensor, mounting flanges and so on to fit your application and to have all components from one source.

Please contact your sales representative for further information.