On small flat grilles with straight airflow, scanning consists of placing a propeller probe 2 cm from the grille and sweeping across its entire supply or exhaust surface. The average flow rate is then calculated over a given period of time.

For optimum grid measurement using the scanning technique, we recommend using helix probes with a diameter of 100 mm. They provide fast, accurate results, particularly on large grids. Sauermann offers a wide range of propeller anemometers such as the Kimo AMI310.

For flat grids with unidirectional flow, the zoning technique (or point-by-point averaging) is also used. This involves dividing the cross-section of the grid into zones and averaging the flow rates in each zone to derive an overall result.

The most reliable values combine average measurements for each zone over the same period of time. The choice of probe depends on the application, but for very low-speed airflows requiring high sensitivity and accuracy, a hot-wire probe is recommended.

Using a cone of the right size will improve efficiency and accuracy. For diffusers larger than 450x450 mm, a balometer is more versatile and specialised. This equipment is essential for multidirectional flow diffusers.

Applying a cone interferes with the airflow by generating turbulence. Our anemometers can compensate for the generated pressure drop by selecting the type of cone in their menu. For balometer measurements, this compensation is achieved by selecting the vent profile on the mobile application.

Whatever the technique or type of probe used to measure airflow, the sensors are subject to physical constraints. They need to be calibrated frequently to guarantee reliable measurements - every year at best.

At Sauermann, we calibrate your anemometers and balometers in our laboratories in the Dordogne. The operation takes place in areas equipped with state-of-the-art speed benches for maximum accuracy and compliance with standards.