Why can't the anemometer replace the air volume hood?
Judging from the test results of the anemometer and the air flow hood, the results differ by as much as 8 times.
However, this problem cannot be solved with a single stick. Not all factories must use the air volume hood for testing. If the requirements are not high, the use of anemometer is sufficient.
However, it is better to use the air volume hood for measurement in newly built factories or old factories with clear requirements on the number of air changes.
The specific reasons why the anemometer cannot replace the air flow meter are as follows:
The anemometer reflects the average wind speed through the selection of test points;
Different forms of diffusers increase the difficulty of measuring the average wind speed;
The air volume hood detects the average wind speed by closing the air outlet.
Anemometer
An anemometer is an instrument for measuring air velocity.
There are many types of it, and the most commonly used one in meteorological stations is the wind cup anemometer, which consists of three parabolic cone empty cups fixed on the bracket at 120° to each other to form the sensing part, and the concave surfaces of the empty cups are all in one direction.
The whole induction part is installed on a vertical rotating shaft, and under the action of wind force, the wind cup rotates around the shaft at a speed proportional to the wind speed.
Use of wind speed meter:
The flow velocity measurement range from 0 to 100m/s can be divided into three sections:
Low speed: 0 to 5m/s;
Medium speed: 5 to 40m/s;
High speed: 40 to 100m/s.
The thermal probe of the anemometer is used for more accurate measurement of 0 to 5m/s; the wheel probe of the anemometer is ideal for measuring the flow velocity of 5 to 40m/s; good result.
An additional criterion for the correct selection of the flow rate probe of the anemometer is the temperature. Usually, the temperature of the thermal sensor of the anemometer is about ±7°C, the rotor probe of the special anemometer can reach 35°C, and the pitot tube is used for +35°C. above.
The anemometer generally measures at a single point, and the accuracy of the test data is not high.
When the tuyere produces vortex/jet flow, the wind speed is not very accurate, and one tuyere needs to measure several points, or even a dozen points to get the average wind speed.
If there are several high-efficiency air supply outlets, it will be very troublesome. It will take a lot of time to test and calculate according to the area of the air outlets. The accuracy is not enough. Therefore, the air volume hood is the most suitable choice for strict dust-free places.
Air Flow Meter/Hood
The air volume hood is mainly composed of three parts: the air volume hood, the base, and the PDA.
The air volume cover is mainly used to collect the air volume and gather the wind to the wind speed homogenizer on the base.
A wind pressure sensor is installed on the wind speed uniformity, and the sensor can reflect the change of the wind speed. Air volume (m³/h).
The display of the air volume hood adopts PDA, and the large-screen LCD display is intuitive, and the data of wind speed, temperature and air volume can be obtained directly, and the recording time interval can be set for continuous parameter recording, so as to analyze the data.
The measured and recorded data are recorded on the memory card and will not be lost. The data can be transferred to the PC through the serial port of the computer for further application.
