Airflow measurements using an anemometer
Measurement of anemometers in ducts
The 16mm probe of the anemometer has proven to be the most versatile. Its size ensures good permeability and can withstand flow velocities up to 60 m/s. The measurement of air flow velocity in ducts is one of the feasible measurement methods, and the indirect measurement protocol (grid measurement method) applies to air measurement.
Anemometer measurements in extracted exhaust air
Ventilation openings significantly change the relatively balanced distribution of the airflow in the duct: high velocity zones are generated on the surface of the free ventilation openings, the rest of the duct is characterised by low velocity zones and vortices are generated on the grids. Depending on the design of the grille, the airflow cross-section is more stable at a certain distance in front of the grille (approx. 20 cm). In this case, measurements are usually made with a large anemometer aperture rotor. This is because the larger aperture allows the averaging of uneven flow rates and the calculation of their average over a wide range.
Anemometer measurements using a volumetric flow funnel at the extraction hole
Even if there is no grid interference at the extraction point, the route of the air flow is undirected and its airflow cross-section is extremely uneven. The reason for this is the local vacuum in the pipe, which funnels the air out in the air chamber, and there is no location that meets the measurement conditions for measurement operations even in the area very close to the extraction. If measurements are carried out using the gate measurement method with an average value calculation function, and if measurements are carried out using the volume flow rate determination method, and if measurements are carried out using the volume flow rate determination method, etc., only the pipeline or the funnel measurement method can provide reproducible measurement results. In this case, measuring funnels of different sizes are available to meet the requirements for use. With the measuring funnel it is possible to generate a fixed cross-section at a certain distance in front of the lamella valve that meets the conditions for flow rate measurement, measure out locate the centre of this cross-section and fix the cross-section, measure out locate the centre of this cross-section and fix the cross-section, measure out locate the centre of this cross-section and fix it there. The measured value obtained by the flow rate probe is multiplied by the funnel coefficient to calculate the volume flow rate pumped.
