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发布人:   发布时间:2021-05-04 16:42:41


Ventilation duct is now widely used in industrial air supply and exhaust, air conditioning and ventilation. The measurement of wind speed and air volume in the ventilation duct is obtained by measuring the pressure conversion, which is a more specialized calculation. The following preparations should be made by the staff of the ventilation duct to measure the wind speed and air volume in the duct:


1、 Measuring position and measuring point


1. Selection of measuring position


The measurement of wind speed and air volume in ventilation duct is obtained by measuring pressure conversion. Reasonable selection of measurement section and reduction of air flow disturbance have great influence on the measurement results. The measurement section should be selected on the straight pipe section with stable air flow as far as possible. The distance between the measuring section and the abnormal parts is at least 1.5 times of the pipe diameter.

测按时如发现任何一个测点呈现零值或负值,注解气流不不变,该断面不宜作为测定断面。气流标的目的偏出风管中 心线15°以上,该断面也不宜作测量断面。

If zero value or negative value is found at any measuring point during the measurement, it indicates that the air flow is unstable, and this section should not be used as the measuring section. The air flow direction deviates from the center line of air duct by 15 ° Above, this section is not suitable for survey.


2. Test hole and measuring point


It is necessary to measure multiple points on the same section, and then calculate the average value of the section.



2、 Measurement of pressure in air duct


Measuring instrument


Gas pressure is usually measured by taking out the pressure signal from the pressure tube inserted into the air duct and reading it on the pressure gauge connected with it. Pitot tube and pressure gauge are commonly used instruments.


1. Pitot


It's a 90 ° The open end of the double concentric tube is communicated with the inner tube to measure the total pressure; There is a circle of small holes on the outer wall near the pipe head to measure the static pressure. The pitot tube correction coefficient processed according to the standard size is approximately equal to 1.


2. S-type pitot tube


The pitot tube is composed of two identical metal tubes in parallel. When measuring, there are two openings in opposite directions. When measuring, the opening facing the air flow is equivalent to the total pressure, and the opening facing the air flow is equivalent to the static pressure. This pitot tube is widely used in the monitoring of dust pollution sources.


3. U-shaped pressure gauge


It is made of U-shaped glass tube, in which the pressure measuring liquid is water, alcohol or mercury according to the pressure range to be measured. The U-shaped manometer is not suitable for measuring small pressure, and the pressure value is converted from the height difference of the liquid column.


4. Inclined micro manometer


When measuring pressure, the opening of the micro manometer container is connected with the higher pressure end in the measuring system, and the inclined pipe is connected with the lower pressure end in the system. The pressure difference acting on the two liquid levels causes the liquid column to rise along the inclined pipe.


The above is the preparation before measuring the wind speed and air volume in the ventilation duct. As long as the preparation is well done, it is possible to obtain more accurate data results in the measurement. I hope the above sharing will help you. If you want to know more, please click: Shandong ventilation duct .


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