How is Anemometer Used in Weather Forecasting and HVAC Applications?
Wind behavior is one of the important aspects of weather forecasting because it can predict the onset of storms or windy day. This behavior is analyzed using instruments such as anemometers. Invented in 1450 by Alberti, the designs of anemometers have evolved over the years, as it has emerged as an important instrument used to measure wind speed/velocity and wind pressure. These wind speed measuring devices offer valuable information for weather forecasting, which may be useful for farmers, pilots, weather forecasting officials, and more. Anemometer are also used in HVAC units for measuring the airflow! How this instrument works in both scenarios? This post offers answer to the same and more.
How to Measure Wind Speed Using an Anemometer in Weather Station?
Based on their application, anemometers are distinguished into two types – velocity anemometers and pressure anemometers. This section focuses mainly on how the velocity of wind is measured using different velocity anemometers. The velocity anemometers are distinguished into more types based on their designs and operating principles. The following are a few common types of anemometers, which although designed for effective wind measurement, differ in terms of their measurement techniques.
- Propellers or Vane Anemometers: These anemometers are designed such that their axis lies parallel to the wind direction, which is why they operate horizontally. The vane anemometer features a tail and a propeller on the same axis. The propeller has a magnet located at its center. When the propeller spins, the magnet rotates on its own. This rotation is captured by the small field sensor near the magnet, and it passes the electric impulses to the processor of the device. Like acup anemometer, the wind speed reading is taken by analyzing the impulse frequencies. Vane anemometers can be availed in large sizes where they are installed above the building or can be availed in pocket-sized designs, which can be fit into your bags or pockets.
Have a look at Triplett Thermo Anemometer Product Range –
|Pocket Thermo-Anemometer - (AM200)||Pocket Thermo-Anemometer - (AM250)||CFM-CMM Thermo-Anemometer|
|10-in-1 Environmental Meter with Air Flow - (EM300)||4" (100mm) Large Vane CFM/CMM Thermo-Anemometer (CFM400)||Thermo-Anemometer + IR (AM320)|
Cup Anemometers: These are the simplest type of velocity anemometers used today. They are commonly found in weather forecasting stations and above buildings. These devices feature four hemispherical cups mounted on a vertical shaft. The cups are located at the end of each arm. These cups can easily catch winds and spin the arms in the direction of the wind. The arms will spin faster at fast wind speeds. When these arms spin, they drive a shaft with a magnet attached to its end. This magnet passes through a sensor, which is known as a reed switch. These switches comprise flexible metal reeds which are included in a glass enclosure. So, when they are exposed to a magnetic field, the reeds join and complete the circuit. This circuit produces an electrical impulse that is sent to the digital processor. The processor considers the impulse frequency to calculate the reading of wind speed.
Over the years, three-cup designs have gained popularity. These designs can work efficiently, irrespective of the direction of wind speed.
- Sonic Anemometers: Developed in the 1970s, these anemometers use ultrasonic sound waves to measure wind speed. The anemometers feature four transducers for north, south, west, and east directions. The machine considers the sonic pulse time of flight between pairs of transducers to measure wind speed. These anemometers can take measurements for a fine temporal resolution such as 20 Hz. This is why it is commonly used for measuring wind speed in turbulent conditions. Sonic anemometers have no moving parts, which makes them an ideal choice for weather stations that are automated and weather buoys.
Working of Anemometer in HVAC Applications
Anemometers are used to measure the airflow in heating and cooling systems. They are placed in the front of the duct or vent. The reading of the anemometer will help you adjust the airflow in commercial or home heating and cooling systems. Generally, hot wire anemometers are used for measuring the airflow in HVAC applications. This device features an electrically heated fine wire, which is supported by needles on the ends. The wire element is heated by passing an electric current to it. This heat is passed to the air through the wire element. The meter sends power to the hot wire to maintain the temperature at zero airflows. This converts the power signal to air velocity, and this measurement is shown on the LCD. The anemometer is generally positioned at certain height on the device. They feature small diameter probes that easily allow measurements in hard-to-reach and tight areas. The measurement ranges of hot-air anemometers range from 0 to 10,000 FPM. These anemometers can withstand temperatures up to 200 degrees Fahrenheit.
If you have been considering an anemometer to measure wind speed or air flow in HVAC application ensure to source it from a trusted source. Triplett offers one of the broadest selections of anemometers, including vane anemometers and thermo anemometers. Most are pocket sized and can be easily carried between locations. They come with automatic power-off feature and water resistant covering. So, if you have been considering wind speed measurement using a vane anemometer then you can choose the model CFM400, which is 4" (100MM) large vane CFM/CMM thermo-anemometer. These anemometers can measure air velocities up to 5900ft/min (30m/s), air flow (volume) to 99999 CFM/CMM, and air temperature (140°F/60°C) for use in HVAC system installation and maintenance, cleanrooms, kitchen exhaust systems, wind power monitoring, construction, sailing/boating, vehicle aerodynamics and many other applications.