Testo portable instruments (Testo 512 digital differential pressure meter and Testo 435-4 multifunction meter) are used for the express analysis of flow data (pressure, velocity, temperature) in AT-11 wind tunnel, test section and during the calibration of Aplisens and DMI-0.1 pressure-measurement instruments. Functionality of Testo 435-4 can be enhanced with attachable special probes.