Air Velocity Meters & Anemometers Review

Air Velocity Meters & Anemometers

The air velocity meter measures air velocity and air pressure. An anemometer is an instrument to measure the speed or velocity of gases either in a contained flow, such as airflow in a duct, or in unconfined flows, such as atmospheric wind. To determine the velocity, it detects changes in some physical property of the fluid or the effect of the fluid on a mechanical device inserted into the flow. Depending on the type of application, the air velocity meter and anemometer are made as a hot-wire AV-meter or a pocket weather AV-meter, both of which can measure air velocity and air pressure.

The results of measuring the air velocity can be stored in memory, depending on the model. The air velocity meter is ideal for taking quick or constant measurements, including monitoring ventilation installations, process checking, and suitable for industry, private workshops, nautical enthusiasts, or other hobbies, etc. An anemometer can measure the total velocity magnitude, the velocity magnitude in a plane, or the velocity component in a particular direction.

AV-Meters for weather stations

The cup AV-meter (used in weather stations) measures the velocity in a plane perpendicular to the axis of its rotation cups. If it is mounted with the shaft perpendicular to the horizontal, it will measure only the component of the wind that is parallel to the ground. Other AV-meters, such as vane anemometers, are used with the tip aligned with the total velocity vector.

The cup AV-meter

Hot-Wire, Vane, or Ultrasonic Anemometer?

Sometimes called wind speed or airspeed meters, AV-meters are generally classified as hot-wire or vane. The hot-wire anemometer is best for accurately measuring airflow at very low velocities (e.g., under 2000 ft/min). Some models are designed to measure velocities as high as 15,000 ft/min but still have very accurate measuring capability down to much lower speeds.

The hot wire anemometer

The vane anemometer relies on a rotating impeller to sense air velocity. Vane anemometers are the best choice for measuring wind speed. Thermo-anemometer is any hot-wire or vane anemometer with the added feature of air temperature measurement.

The vane anemometer

Ultrasonic AV-meters use ultrasonic sound waves to measure wind velocity. They measure wind speed based on the time of flight of sonic pulses between pairs of transducers. Sonic anemometers can take measurements with a very fine temporal resolution, 20Hz or better, which makes them well suited for turbulence measurements.

Sonic anemometers

(Also) - Hygro-thermometer/psychrometer AV-meters include the features of a thermo-anemometer and a humidity sensor, giving complete environmental information. Data-logging AV-meter is designed to store measurements for later review and/or download logged air velocity readings to your computer for review, graphing, and further analysis.

AV-Meters & Air Duct Traversing

Anemometers are widely used for air duct balancing. This is accomplished by placing multiple AV-meters in a cross-section of the duct or gas pipe and manually recording the velocity readings at numerous points. The mass flow rate is obtained by calculating the mean velocity and multiplying this by the density and by the cross-sectional area measurement of the duct.

Features to look for in your AV-meter

Thermo-anemometers with remote sensors are the most popular models for HVAC applications. Available with vane or hot-wire sensors, they display readings in multiple engineering units, including ft/min, m/s, mph, knots, and km/h. Simultaneous displays of velocity and temperature.

  • Remote sensors. Easy to view the display on the meter while reaching and placing the remote sensor in ducts and exhaust hoods.
  • Hot-wire sensors. For measuring low airspeed; allows direct access into ducts.
  • Humidity. Plug-in humidity probe converts your air-flow meter into a humidity meter.
  • PC Interface. To view and record trends in airflow and temperature measurements.

Measuring Air Velocity to suit the conditions, with the features you need:

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