Durag D-R 220 Dust and Opacity Monitor

Durag has decided to discontinue the D-R 220 by 31.12.2024 without replacement.
If you still need the D-R 220, you can order it until 30.09.2024.
Repairs, delivery of spares and wear and tear parts will be available for up to 5 years after the date of discontinuation.

Alternative product D-R 290 (2. G)

The D-R 290 works according to the transmission principle. The measurement is continuous, non-contact and without sampling in the exhaust gas flow. The D-R 290 is particularly suitable for monitoring medium to high dust concentrations.

For tunnel projects SMART/AQM

Air quality monitor with IoT visible opacity and gas sensor for use in tunnels. Visibility measurement is based on the scattered light principle, gas measurement with up to 3 electrochemical cells.

The DURAG D-R 220 was a compact and cost effective transmittance dust and opacity measuring device for monitoring medium to high dust concentrations in dry flue and process gas.

Key Benefits

  • Non-contact measuring method
  • Continuous measurement of opacity and dust concentration
  • Suitable for medium or high dust concentrations on short to medium measuring lengths
  • Automatic internal self-test, zero point and reference point check
  • Manual contamination and linearity check
  • Extremely low-maintenance due to self-test functions and LED source
  • Easy installation and commissioning with universal operating unit and adjustment tool
  • Convenient operation including remote access capability
  • Cost-effective, small measuring system
  • Operation with or without control unit


Suitable for dust concentration and opacity measurement

  • Measurements with variable flow speeds
  • Visibility Monitoring


  • Power industry
  • Biomass incineration
  • Waste incineration
  • Cement industry
  • Crematories
  • Process monitoring

Opacity measurements on ships

  • Ro-Ro ships
  • Cruise ships
  • Container ships

Also suitable for

  • Cost effective process monitoring
  • Filter monitoring
  • Measurement of ambient air dust-load in halls or warehouses

Download Specifications


Stack, Process & CEMS


Flue gas type Air, flue gas, non flammable process gas
Flue gas temperature Above due point,
≤ 200 °C (≤ 392 °F) standard,
other on request
Inner duct pressure (relative to ambient pressure) -50 … +10 hPa standard,
-50 … +50 hPa option
Flue gas relative humidity 0 … 95 % RH, non-condensing
Stack/duct inner diameter 0.4 … 10 m (1.3 … 32.8 ft)
Measuring principle Measuring the optical transmission of visible light which passed a measuring path twice
Certificates CE, Pattern Approval Certificate PRC
Measuring location In-situ, non-contact. Mounted at stack, measurement across the stack, purged sensors are not in contact with flue gas
Self-check, protective functions LED light source: no readjustment needed
Automatic internal self-test
Automatic zero and reference point check (option)
Manual contamination check and linearity check (option)
System components D-R 220 M measuring device
D-R 220 R reflector
D-R 220 SPF purge flange
D-R 220 CLP clamping ring fastener
D-R 220 N zero point reflector (option)
D-R 220 E adjusting flange with tube (option)
D-ISC 100 universal operating unit (option)
Purge air and power supply unit (option)


Physical measuring valueTransmission, opacity

Derived measuring values Opacity (PLC), optical density, dust concentration in mg/m3, mg/Nm3 (after gravimetric calibration), extinction coefficient, visibility
Measuring range transmission 100 … 0%
Output range transmission Freely programmable
Measuring range opacity 0 … 100%
Output range opacity Freely programmable
Measuring range extinction 0 … 1.6
Output range extinction Freely programmable
Measuring range dust concentration 0 … 5000 mg/m3 (depending on calibration)
Output range dust concentration Freely programmable
Lowest detection limit 0.2 % transmission
Combined standard uncertainty acc. to QAL1, DIN EN 14181 less than 0.013 Ext (2 mg/m3 for particle size 1 … 2µm, duct ID 5m (16.4 ft))
Light source LED
Process connection Adjusting flange, bolt circle 100 mm, tube ID = 59 / 83 / 105 mm
Purge air connection For hose Ø 25 mm
Electrical connection DURAG standard device connector M23 male
Digital interfaces RS 485 Modbus RTU, bi-directional communication, USB (Service)
Analog outputs 1 x 4 … 20mA, 400 Ohm, isolated, assignment parameterisable
Digital outputs 2 x contact NO, permissible load 60 VDC / 30 VAC / 0.5 A,
function can be assigned. Typically: maintenance, failure
Power supply Sensor supply voltage 24 VDC, 0.4 A
Ambient temperature (operational) -20 … +50 °C (-4 … 122 °F)
IP protection class (IEC 60529) IP65
Dimensions (HxWxD) 150 x 132 x 214 mm (150 x 132 x 331 mm with purge air flange)
Weight 2.7 kg
Material Housing: Polyamide, RAL 5017, fire class B1 (UL 94 V0),
Purge air flange: 1.4571 (316 Ti)
Process connection Adjusting flange, bolt circle 100 mm, tube ID = 59 / 83 / 105 mm
Ambient temperature (operational) -20 … +50 °C (-4 … 122 °F)
IP protection class (IEC 60529) IP65
Dimensions (HxWxD) 126 x 132 x 101 mm (126 x 132 x 218 mm with purge air flange)
Weight 1.6 kg
Material Housing: Polyamide, RAL 5017, fire class B1 (UL 94 V0),
Purge air flange: 1.4571 (316 Ti)

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