Learn to distinguish between different anemometers
On site anemometer measurement is mainly divided into three types based on principle: pressure difference type, impeller type, and hot ball type
The differential pressure method is a classic method for measuring flow velocity in fluid mechanics, which mainly relies on Pitot tubes and differential pressure gauges to measure the dynamic pressure, and then calculates the flow velocity based on the Bernoulli equation. The advantages of this method are low detection limit and high sensitivity, but the requirement for uniformity of the convective field is high. When measuring in the environment, it is easy to be inaccurate due to uneven flow field. Therefore, the pressure difference method is mainly used to measure wind speed in ducts.
The main principle of the hot ball type is that the probe is set at a constant temperature, and air passing through the probe will carry away heat. At this point, the probe will be heated to the set temperature, and during this process, electrical signals will be collected by the instrument and converted into wind speed based on this. The advantages of this method are high sensitivity, large range, and adaptability to environmental measurement. The disadvantage is that the platinum wire connecting the hot ball in the probe is relatively fragile, and if not careful during use, it can easily cause damage to the probe and cannot be repaired. At present, the domestic hot ball anemometer is still an old-fashioned anemometer, and the Air Conditioning Institute of the Construction Research Institute has a more advanced alternative technology, replacing the hot ball with a ceramic hot column, which has much better strength than the hot ball.
The impeller type mainly relies on the wind to rotate the impeller, generating electromagnetic signals for measurement. The advantage of this method is that the instrument is relatively durable and commonly used for long-term measurement. The three cup anemometer used in meteorological observation also shares the same principle, but the disadvantage is that the sensitivity is slightly poor.
Wind speed instruments belong to the category of safety protection and environmental monitoring measuring instruments, and are mandatory calibration measuring instruments stipulated by China's Metrology Law. Safety requirements for the use of anemometers:
1. In use, if the anemometer emits abnormal odor, sound, or smoke, or liquid flows into the interior of the anemometer, please immediately shut down and remove the battery. Otherwise, there is a risk of electric shock, fire, and damage to the anemometer.
2. Do not expose the probe and anemometer body to rain. Otherwise, there may be risks of electric shock, fire, and personal injury.
3. Do not touch the internal sensor part of the probe.
4. When the anemometer is not in use for a long time, please remove the internal battery. Otherwise, the battery may leak liquid, causing damage to the anemometer.
5. Do not place the anemometer in areas with high temperature, humidity, dust, and direct sunlight. Otherwise, it will cause damage to internal components or deterioration of the performance of the anemometer.
6. Do not use volatile liquids to wipe the anemometer. Otherwise, it may cause deformation and discoloration of the anemometer housing. When there are stains on the surface of the anemometer, a soft fabric and neutral detergent can be used to wipe it.
7. Do not drop or press the anemometer heavily. Otherwise, it will cause malfunction or damage to the anemometer.
8. Do not touch the sensor part of the probe while the anemometer is charged. Otherwise, it will affect the measurement results or cause damage to the internal circuit of the anemometer.
