A hot wire anemometer measures air velocity by detecting cooling effects on an electrically heated, ultra-thin wire or film sensor exposed to airflow. This thermal transfer principle allows extremely precise, low-velocity measurements and rapid response to turbulent conditions. Hot wire anemometers are sensitive instruments requiring careful handling and periodic calibration.
Technical Details
Hot wire anemometers can measure velocities from near zero to 8,000 fpm with accuracy within 1-2% of reading. The sensor diameter is typically 5-70 micrometers, providing superior spatial resolution in complex flow fields. Response time is under 100 milliseconds, enabling detection of rapid velocity fluctuations. Instruments require regular recalibration and are sensitive to dust and contamination, necessitating frequent probe cleaning.
HVAC Applications
These instruments are employed for precision velocity mapping in research applications, laboratory commissioning work, and complex flow analysis in large commercial systems. They excel where low velocities or turbulent conditions require detailed measurement.
Practical Significance
Hot wire anemometers provide data quality superior to mechanical designs but require technical expertise and careful maintenance. Their use is typically limited to specialized commissioning work rather than routine service.