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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.


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 type Air, 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 humidity 0 … 100 % RH, condensation allowed
Flue gas flow velocity 0 … 40 m/s
Stack/duct inner diameter 0.5 … 13 m, temperature dependent

Measuring principle Measurement of direction-dependent transition times of ultrasonic pulses, thereof calculation of flow speed and volume flow
Conformities 2010/75/EU
13., 17., 27., 30. BImschV
TA Luft
EN 14181
EN 15267-1, -2, -3
DIN EN 16911-2
40 CFR 60 US EPA PS6
Certificates CE, QAL1 (DIN EN 14181 / DIN EN ISO 14956 / DIN EN 15267-3), MCERTS, EAC
Measuring location In-situ, non-contact. Mounted at stack, measurement across the stack, purged sensors are not in contact with flue gas
Measuring path length 1 … 15 m, temperature dependent
Measuring angle 45° ±15° relative to the flow direction
Self-check, protective functions Automatic internal self-test
Automatic zero- and span check
System components D-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 value Direction-dependent transition time of ultrasonic pulses
Derived measuring values Flow velocity and direction, volume flow at operating conditions or normalized
Measuring range gas velocity 0 … 40 m/s
Output range gas velocity Freely programmable
Measuring range volume flow 0 … 5000000 Nm3/h
Output range volume flow Freely programmable
Measuring range temperature 0 … 400 °C
Output range temperature Freely programmable
Resolution 0.1 m/s
Lowest detection limit 0.2 % of the certified measuring range
Combined standard uncertainty
acc. to QAL1, DIN EN 14181
0.34 m/s
Integration time 1 … 180 s, freely programmable
Process connection D-FL 220 E mounting tube with flange, DN80 PN6, tube ID = 100 mm
Digital interfaces RS 485 Modbus RTU, bi-directional communication, USB (Service)
Analog outputs 1 x 4 … 20 mA, 400 Ohm, isolated, assignment parameterisable
Digital outputs 2 x contact NC/NO, permissible load 60 VDC / 30 VAC / 0.5 A, function can be assigned. Typically: maintenance, failure
Power supply Sensor 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
Weight 6.5 kg (sensor head 610 mm with purge air flange, weight depending on version)
Material Housing: 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 interfaces Purge air connector OD = 40 mm
Air supply capacity 10 … 40 m3/h (per measuring device)
Process connection DN80 PN6
Dimensions (HxWxD) 190 x 200 x 90 mm
Weight 2.9 kg
Material Stainless steel 1.4571 (316 Ti)

Process connection DN80 PN6
Dimensions (HxWxD) 108 x 335 … 2135 mm
Weight 5.5 kg (L = 335 mm, depending on version)
Material Stainless steel 1.4571 (316 Ti)
GFK (Durabest 180)


The universal operating unit  D-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  D-ESI Service and Parameterisation Software  assists you to manage all your DURAG sensors connected in one network system via a uniform graphical Interface.

Supply unit

  • 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.



Product overview emission monitoring / DE (4 MB)
Product overview emission monitoring / EN (4 MB)
Guidance book EU regulations / DE (4 MB)
Guidance book EU regulations / EN (3 MB)

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