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Key Benefits

  • Precise gas volume and velocity measurements to complete your emissions monitoring package
  • Measurement possible below dew point, at high temperature and for high dust concentrations
  • Reliable, low-maintenance equipment

Flow monitors that deliver real process insight

In order to gain real insight from monitoring process and stack emissions, you also need precise measurements of gas volume and velocity. Flow monitoring completes your emissions monitoring package, giving you all the data you need to comply with the reporting requirements of environmental legislation.

We’ve chosen the best flow monitors on the market

Our many years of experience have led us to the conclusion that Durag flow monitors are the best for almost every application.


Precision is guaranteed. Durag’s solutions cater for gas measurement in gases below the dew point, at very high temperatures, with high dust concentrations, at low speeds and at high pressure. Maintenance is minimal and requires little effort. The systems are certified according to EN 15267-3, MCERTS and TÜV, so you can be assured they’ll deliver on the tasks required of them.

Reliable measurements of gas volume and gas velocity

When we equip emissions monitoring systems, our most commonly chosen flow monitors are the Durag D-FL 100 and D-FL 220.
Durag D-FL 100
The D-FL 100 measuring system operates according to the differential pressure principle. The probe has two separate chambers between which the flow builds up a differential pressure. The evaluation unit determines the gas velocity and the volume flow (norm conditions or standard conditions) from the differential pressure, taking into account gas temperature and gas pressure. With this system, you can have continuous measurement of normal volume flow and gas velocity. And it can be operated with or without a control unit, via remote access with web interface. The flow monitor can also be used at high temperatures or high pressure and both for large or small stack cross-sections.D-FL 100 Volume Flow Meter
Durag D-FL 220
Measuring system for ultra-sonic measurement of flow and volume flow, especially for wet and aggressive gases. The measuring system works according to the acoustic transit time differential method. Two identical transducers mutually send and receive short ultrasonic pulses. The system calculates the precise gas velocity and volume from the direction-dependent transit time difference. This device provides reliable measurement of gas velocity even at high temperatures. There’s an automatic zero point and reference point control. And it can be operated remotely with web interface. As a non-contact system, it's subject to very little wear, giving you maximum availability and reliability.D-FL 220 Volume Flow Meter

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