Learn how to select an anemometer probe
1、Thermal probe of anemometer
The working principle of the thermal probe of anemometer is based on the cold impact airflow to take away the heat from the thermal element, with the help of a regulating switch to keep the temperature constant, then the regulating current and the flow rate are proportional to each other. When using a thermal probe in turbulent flow, air currents from all directions simultaneously impinge on the thermal element, thus affecting the accuracy of the measurement results. When measuring in turbulence, the thermal anemometer flow rate sensor tends to show a higher value than the rotating wheel probe. The above phenomenon can be observed during duct measurements. Depending on the different designs used to manage duct turbulence, they can occur even at low speeds. Therefore, the anemometer measurement process should be carried out in a straight part of the duct. The starting point of the straight section should be at least 10 x D (D = pipe diameter in CM) away in front of the measurement point; the end point should be at least 4 x D behind the measurement point. The fluid section shall not be obstructed in any way. (Angles, heavy suspension, objects, etc.)
2、Rotor probe of anemometer
The working principle of anemometer's rotating wheel probe is based on the conversion of the rotation into electrical signals, first through a proximity inductor, the rotation of the wheel for "counting" and produce a pulse series, and then converted by the detector processing, you can get the rotational speed value. The large diameter probes (60mm, 100mm) of the anemometers are suitable for measuring turbulent flows with small or medium velocity (e.g. at the outlet of pipelines). The small diameter probe of the anemometer is more suitable for measuring the airflow where the cross-section of the pipe is more than 100 times of the cross-section of the probe.
