Case study

Improved coffee roasting efficiency thanks to continuous volume flow measurement
Manufacturer of coffee roasting equipment | AirFlow P
Customer: PROBAT, manufacturer of coffee roasting equipment
Installation point: In the exhaust pipe of a coffee roasting plant
Function: Control the volume flow to ensure high roaster efficiency through optimal energy transfer to the coffee bean


PROBAT is a manufacturer of coffee roasting equipment. PROBAT’s roasters are operated according to a special procedure to make the roasting process as efficient as possible.

This procedure enables PROBAT to use a large part of the hot air generated to support the process and thus save energy. The company saves money through lower energy costs while maintaining the same product quality.

In order to be able to operate these roasters in an energy-efficient manner, it is important to know which air volume flows through the roaster. Depending on the type of coffee and roasting profile, different volume flows may be required. A correctly set and controlled volume flow ensures high roaster efficiency through optimal energy transfer to the coffee bean. If the volume flow is set incorrectly, the energy transfer to the bean would have to be adjusted via the temperature of the roasting gas, which would have a significant impact on the roaster’s efficiency.

The air volume is thus an important indicator for the control and quality of the roasted coffee. PROBAT was looking for a way to measure the volume flow in the process. Due to the relatively high dust load and the high process temperature (300°C) during the roasting process, a special solution had to be found.

Process data

  • Dust loading: 1 – 10 mg/m3
  • Diameter: 250 mm
  • Process temperature: 150°C – 300°C


The AirFlow P for high temperatures is designed for continuous measurement of air volume in dust-laden applications up to 800°C. It is an electrodynamic sensor that does not require any modifications in the process.

In the application described, the sensor was installed in an exhaust pipe of a coffee roasting plant. Thanks to a simple process connection and a controller, it provides a stable measurement signal of the volume flow in the pipeline via a controller.

This position is ideally suited for volume flow measurement, as the sensor is installed close to the roaster and the necessary dust loading was ensured.

With the signals from the AirFlow P, PROBAT is able to control the coffee roaster even more efficiently and to store different volume flows for different types of coffee and roasting profiles in the control system.


  • Reduced maintenance due to optimised volume flow settings
  • Increased safety due to less residues in the exhaust air system (sparking)
  • Increased separation efficiency of the roasting cyclone due to operation in the working area
  • Optimised operation of the roaster and thus energy savings
  • Improved product quality and consistency through continuous volume flow measurement
  • Simple and fast sensor connection
  • Further possible applications in the inlet zone

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