Thermal Flow Sensors
Thermal flow sensors work of the calorimetric principle and are suited to a wide range of flow monitoring applications. They are easy to install and independent of temperature and pressure. ATEX versions are available.
The standard one-piece sensors are available in a range of materials including special materials such as Hastelloy, Titanium or even PTFE for use in aggressive media. These flow controllers are highly reliable units for the water industry, automation industry, chemical industry, and wherever flows have to be monitored in a safe, robust and low-maintenance manner.
The flow controllers are either screwed into the side of the pipe or added to the line itself in the form of inline sensors. Different
versions are available - either compact flow sensors with integral electronics, or flow sensors with remote amplifiers.
The function of the flow sensor is based on the thermodynamic principle. The sensor is heated internally a few degrees C compared to the medium into which it projects. When the medium flows, the heat generated in the sensor is conducted away by the medium, i. e. the sensor cools down. The temperature within the sensor is measured and compared to the temperature of the medium. The state of flow can be derived for each medium by the temperature difference attained.
Thermal flow sensors for liquids
The thermal flow sensors for use on liquids are available in 
either compact form, with the sensor and the electronics combined in one unit, or you chose a separate amplifier and controller.
The flow sensors operate on the thermodynamic or calorimetric principle, without moving parts, which means they are robust and resistant to soiling.
Thermal flow sensors for gases
The thermal flow sensors for use on gases are available in 
either compact form, with the sensor and the electronics combined in one unit, or you chose a separate amplifier and controller.
The flow sensors operate on the thermodynamic or calorimetric principle, without moving parts, which means they are robust and resistant to soiling.
Materials for construction and chemical resistance for flow sensors
Materials for construction and chemical resistance for flow sensors 
Thermal flow sensors - installation guidance
The flow sensing probe is made of special steel in one piece, using a robust electronic and mechanical construction. By means of this, absolute tightness and a high pressure resistance is obtained. The chemical stability of the sensor material must be verified individually for every application Assembly is independent of flow direction. A basic requirement is that the sensor tip must be completely surrounded by the monitored medium, whether the medium flows or is at rest. With smaller cross sections care must be taken that the sensor tip does not narrow the pipe profile considerably.
Flow sensor setting instructions
Switching point
Setting with flow off
- Install the sensor in the flow duct and apply power. Wait for ready state.
- Carry out the potentiometer adjustment so that the red LED lights up.
- When the medium begins to flow, at least one green LED should light up.
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