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About anemometers
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Introduction
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How do anemometers work?
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Application areas of anemometers
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This will help you find the appropriate anemometer
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Our practical tip: Need for calibration
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FAQ - Frequently asked questions about anemometers
Introduction
Anemometers are measuring instruments that measure the speed of a flow field . Most of the time, these are wind gauges, and sometimes the flow rate of liquids is also determined. The measurement takes place either in the cross-section of a box, for example, or locally in the free field.
In our shop you will find different types of anemometers with different accuracy tolerances. In addition to the flow speed, many devices also collect other useful data such as temperature, humidity and dew point.
How do anemometers work?
Anemometer with large impeller allows a more accurate measurement
The oldest type of anemometer is the vane anemometer , also known as the shift cross anemometer. Later technical innovations use other physical principles to determine air velocity and volume flow. A impeller anemometer functions like a windmill with additional evaluation function: The air flowing through drives the impeller wheels, resulting in the rotation, which is evaluated using a counter.The time span for a full revolution is transferred to the counter with a mechanical ratio, which then determines the current wind speed and transmits it to a display.
The flow rate of gases such as air or liquids such as water is expressed in meters per second m/s. . In addition to the wind speed of gases such as air, the volume flow is an important variable that is determined using anemometers. The volume flow refers to the quantity (volume) of gases (or liquids) flowing through a certain area (cross-section).
Depending on the design and technology used, anemometers rely on different principles. The most important variants and their functional methods have been used reliably for many years.
| Design | Function |
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| Fan wheel | The classic and one of the oldest forms of measurement technology for wind speeds are vane anemometers. The impeller provides a constant size for the penetrating air flow. Other variables, such as frictional resistance and weight of the wings, can be included in the measurement of speed. The wind speed of the air flow is then determined. |
| Hot wire | A thermal anemometer heats a heating wire to a fixed temperature to measure the speed of the air flow. The air flow velocity is calculated from the cooling and the speed of this cooling as well as the ambient temperature. |
| Tailpipe | A Pitot tube or similar measuring sensors measure the air pressure generated by the incoming air. Finally, the speed of the air flow is determined from the data obtained. |
Modern anemometers usually have digital displays and determine a variety of useful indicators. Probes with measuring sensors are used as accessories for measuring in channels and shafts. To evaluate the collected data, some anemometers have USB interfaces or Bluetooth interfaces and the computer software included in the delivery, or they transfer the measured values directly to smartphones and tablets via mobile apps.
Application areas of anemometers
Anemometers can be found in many areas. The oldest and most well-known application is the determination of wind speed within the framework of meteorological weather observation . However, modern weather meters, which in their role extend far beyond the determination of wind speeds, have much more functions. Anemometers in the narrower sense are installed today in exposed places as wind warning systems.
By the way: Weather measuring devices and weather stations can also be found in our shop.
Anemometer in building automation
Measuring hood for larger air outlets for measuring the volume flow
Anemometers are the most common, modern application in building automation . Here, the wind gauges are used to control ventilation and air conditioning systems. For example, an anemometer can be used to measure the number³ of cubic meters (m) of air flowing through the outlet of a ventilation duct within a second or minute to check the operation of such systems.
To obtain accurate readings, funnel attachments are often used that direct the entire air flow to the measuring point (Figure 2). In ducts and pipes, however, the measurement is made using probes (Figure 3).
The volume flow of draft air can also be determined using anemometers. Small pocket anemometers are usually sufficient for this purpose.
Anemometer in industrial use
Anemometer with pressure sensor for measuring channels
Anemometers are also used in commercial and industrial applications to control the dimensioning of channels of any kind and flow control in technical systems.
For example, air conditioning and anemometers are used to ensure the overpressure in operating rooms of hospitals which are to transport the germ load to the outside.
Wind turbines also contain anemometers. Another major field of application for anemometers is the weather of mines, which aim to achieve safe working conditions under days.
This will help you find the appropriate anemometer
There are different types and modes of operation of anemometers. The most common are:
- Vane anemometers are usually particularly handy. The impeller is either fixed in or on the housing or is connected to the meter via a cable, which gives a little more flexibility when performing the measurement. These classic anemometers bring additional measurements (depending on the model).
- A hot-wire anemometer can measure not only the flow speed, but also the temperature of the air flow and other variables. A thermal sensor is required for temperature measurement. The thermal anemometer is particularly compact and includes a telescopic rod, which can also reach the air flow from a distance. Hot-wire anemometers are particularly sensitive and can measure even low air speeds.
- Similar to a hot-wire anemometer, the pressure anemometer is not equipped with a impeller, but with a slim nozzle. These measuring instruments can be held in the air flow like impeller anemometers and thus determine the speed of the air flow via a pressure/differential pressure measurement.
For the selection of a suitable anemometer for your application, you can make further, different settings in our shop.
Temperature measuring range
Choose a suitable temperature range based on your environmental conditions, because the density of gases and liquids changes depending on the temperature. If your anemometer is not approved for thermal conditions, inaccurate measurements may result or the technique may be damaged. Temperatures are available between – 10° and + 60 C.
Measurement range - wind speed
The expected range of wind speed is important for meaningful scaling. The lower section is about the sensitivity of the measuring device, the upper limit is the maximum value up to which you can reliably display speeds. Underdimensioning of the measuring range can cause damage to the anemometer. Measuring instruments are available for 0 to 80 m/s . Other units of speed are displayed directly on some meters, otherwise conversion is necessary by hand or using freely available online converters.
calibration
This provides information on the standard to which the devices are calibrated. In particular in the commercial sector, you should inquire in advance about the applicable regulations.
- DAkkS: The German Accreditation Body is a national body that carries out product tests and, in some cases, conformity tests with technical standards such as DIN and ISO standards, thereby ensuring international harmonization of quality characteristics.
- ISO: ISO 17713 is an international guideline for wind measurements. The certification is considered to be comparatively favorable for manufacturers, since often no accredited process is behind the test.
- Factory default (without certificate): Factory standard without certificate performs comparative tests with factory reference devices. Calibration is not performed by an accredited laboratory.
- Factory standard (with certificate): Factory standards with certificate are accepted internationally if the test was not carried out by the manufacturer itself but by an independant third party. This confirms the correct delivery status of new devices.
Our practical tip: Need for calibration
For the manufacturers, external quality checks involve considerable costs. The certification process is a separate market with a jungle of regulations. If a measuring device does not have an internationally comparable approval, it should not necessarily disturb you as a private user, because it does not necessarily say something about the quality .
In fact, such policies and regulations usually only have to deal with industrial buyers whose companies maintain their own quality departments to comply with high standards.
Accuracy
The accuracy of the anemometer is crucial for the reliable collection of measured values . Tolerance deviations of measuring instruments are often expressed in %. The smaller the percentage, the more accurate the data determined. Some manufacturers instead specify the tolerated deviation with absolute values in the unit to be measured, e.g. 0.2 m/s.
Air flow
The air flow rate is a measure of anemometers for determining volume flows . It specifies the flowing quantity in m3 per time unit. In our shop you will find a wide range starting at 0.024 m3/min.
FAQ - Frequently asked questions about anemometers
Air speed meter with flexible impeller for measurement
How often can an anemometer be used?
Anemometers can be used infinitely many times as long as they last. However, proper use and regular calibration are important. The manufacturers and other service providers support this. The calibration interval can be one year or several years, depending on the model and use.
How exactly does an anemometer measure?
An anemometer measures very precisely with a measuring accuracy of 3% or less (depending on the model). The correct use of the anemometer is of primary importance.
Depending on the design and measurement technology, additional extras may be required or a specific procedure may have to be followed. The manuals for the devices explain the correct procedure.