The ESF duct airflow transmitter registers the airflow speed according to a thermal principle based on the fact that the cooling action of air increases with airspeed. The action is measured and converted to a 4 – 20mA or a 0 – 10 V signal corresponding to airflow speeds from 0 – 8 m/s (0 – 1575 ft/min) or 0 – 16 m/s (0 – 3150 ft/min).
