Hydrous media
Water has good thermal properties, which allows the calorimetric measuring principle to show its strengths and reliably determine the flow velocity.
In such applications, however, turbulence of the medium and varying flow velocities can influence the measurement result. Deposits or biofilms can also form, which impair thermal conductivity.
Glycols and oils
Glycol protective films and oils have a lower thermal conductivity compared to water. The exact composition of the medium influences these physical properties, which is why a media curve should be used for the respective medium. In addition, the viscosity of oils changes depending on the temperature and temperature stratification can occur within the pipe, which must be taken into account during measurement and installation.
Gaseous media
Air has a very low thermal conductivity compared to liquid media and requires a comparatively longer stabilisation distance in the event of turbulence. As a result, rapid temperature fluctuations and temperature stratification have a strong influence on the measurement signal. Air is a compressible medium, which means that the pressure influences the density and this in turn determines the thermal conductivity of the medium. The thermal flow principle measures the flow velocity (m/s) and there is no conversion to standard conditions (Nl/min). Deposits such as soot and condensate on the measuring tip can also impair the measurement.