Air Velocity Meters & Anemometers Review Feb. 2, 2015

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 change 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, 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.

Hot Wire, Vane or Ultrasonic Anemometer?

Sometimes these types are called wind speed or air speed meters, AV-meters are generally classified as hot wire or vane. The hot wire anemometer is best for accurately measuring air flow at very low velocities (eg., 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 vane anemometer relies in a rotating impeller to sense air velocity. Vane anemometers are the best choice for measuring wind speed. A thermoanemometer is any hot wire or vane anemometer having the added feature of air temperature measurement.

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 transducers. Sonic anemometers can take measurements with very fine temporal resolution, 20Hz or better, which makes them well suited for turbulence measurements.

(Also) - Hygro-thermometer/psychrometer AV-meters include the features of a thermo anemometer and a humidity sensor giving a customer's complete environmental information. A 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 sensor, 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 meter while reaching and placing remote sensor in ducts and exhaust hoods.
  • Hot wire sensors. For measuring low air speed and 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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