What instrument is used to measure airflow in ducts?

The instrument used to measure airflow in ducts is an anemometer. An anemometer is specifically designed to measure the velocity or speed of air moving through a space, making it ideal for assessing airflow in HVAC systems. There are various types of anemometers, including vane anemometers, which use rotating blades to gauge wind speed, and hot-wire anemometers, which measure changes in temperature to determine air velocity. This capability is crucial in HVAC applications to ensure proper air distribution and system efficiency.

In contrast, the other instruments listed serve different functions. A barometer measures atmospheric pressure, which is not directly related to air velocity in ducts. A thermometer measures temperature, essential for assessing comfort levels and system performance, but it does not provide airflow measurements. A manometer is used to measure liquid pressure, often in gas and fluid systems, but it does not measure airflow directly.