Learn to tell the difference between different anemometers
On-site anemometer measurement is mainly divided into three types: differential pressure type, impeller type, and thermal ball type.
The differential pressure method is a classic method for measuring flow velocity in fluid mechanics. It mainly relies on the pitot tube and differential pressure gauge to measure the dynamic pressure, and then calculates the flow velocity according to the Bernoulli equation. The advantage of this method is that the detection limit is low and the sensitivity is high, but it has high requirements on the uniformity of the flow field, and it is easy to be inaccurate due to the uneven flow field when measuring in the environment. Therefore, the differential pressure method is mainly used to measure the wind speed in the air duct. .
The main principle of the hot bulb type is that the probe sets a constant temperature, and the heat will be taken away after the air flows through the probe. At this time, the probe will be heated to the set temperature. During this process, electrical signals will be collected by the instrument, and then Calculate the wind speed. The advantages of this method are high sensitivity, large measuring range, and suitable for environmental measurement. The disadvantage is that the platinum wire connected to the heat ball in the probe is relatively fragile. If you are not careful during use, the probe will easily be damaged and cannot be repaired. At present, the domestic thermal bulb anemometer is still an old-fashioned anemometer. The Air Conditioning Institute of the Construction Research Institute has a more advanced alternative technology, replacing the thermal bulb with a ceramic thermal column, which is much stronger than the thermal bulb.
The impeller type mainly depends on the wind to blow the impeller to rotate and generate electromagnetic signals to measure. The advantage of this method is that the instrument is relatively durable and is often used for long-term measurement. The three-cup anemometer used in meteorological observation is also based on the same principle. The disadvantage is that the sensitivity is slightly Difference.
The wind speed instrument belongs to the measuring instrument of safety protection and environmental monitoring, and it is a compulsory verification measuring instrument stipulated by the metrology law of our country. Requirements for the safe use of anemometers:
1. During use, if the anemometer emits abnormal smell, sound or smoke, or liquid flows into the anemometer, please shut down immediately and take out the battery. Otherwise, there will be danger of electric shock, fire and damage to the anemometer.
2. Do not expose the probe and anemometer body to the rain. Otherwise, there may be danger of electric shock, fire and personal injury.
3. Do not touch the sensor inside the probe.
4. When the anemometer is not in use for a long time, please take out the internal battery. Otherwise, the battery may leak and cause damage to the anemometer.
5. Do not place the anemometer in places with high temperature, high humidity, dust and direct sunlight. Otherwise, it will cause damage to internal components or deterioration of the performance of the anemometer.
6. Do not wipe the anemometer with volatile liquid. Otherwise, the shell of the anemometer may be deformed and discolored. When the surface of the anemometer is stained, it can be wiped with soft fabric and neutral detergent.
7. Do not drop or put heavy pressure on the anemometer. Otherwise, it will cause failure or damage of the anemometer.
8. Do not touch the sensor part of the probe when the anemometer is charged. Otherwise, it will affect the measurement results or cause damage to the internal circuit of the anemometer.
