Most airflow sensors currently available for data centers or server rooms are analog sensors. They just report if airflow is present based on a mechnical trigger with some units allowing you to manually set the trigger level.
ServersCheck introduces one of the first standalone digital airflow sensors for data centers. The sensors measure airspeed in meters per second and report it as such to the base unit, the SensorGateway.
The digital airflow sensor probes can measure air speeds of up to 3m/s. This equivalent to air speeds of up to 6.7 mp/h or 10.8 km/h