Air measurements in the room. Airflow measuring port

An important factor for comfortable human lifeis clean air. Many enterprises pollute the atmosphere with various substances that affect health. Having made measurements of atmospheric air, scientists make disappointing conclusions. Therefore, great importance is given to ventilation and air conditioning systems. They help to make life better.

General information

Ventilation and air conditioning systems shouldfunction well for a long time. To do this, it is necessary to carry out a professional setting, as well as timely maintenance. The list of technical works also include air measurements.

This procedure is carried out in accordance with the developed techniques.

Flow rate

The movement of air through the system occurs witha certain speed influenced by various factors. First of all, it depends on the constructive solution of the ventilation system (that is, the section and length of the ventilation ducts). It is these indicators that affect air flow. To determine the speed of the flow, it is necessary to make measurements of air, namely its dynamic pressure at several points. The average rate and will show the air velocity in the system.

It should be noted that this indicator forThe room is essential for living rooms. The air enters them unidirectional flow. Indoor air measurements are made primarily for residential areas. There is an unidirectional flow.

Why carry out air flow measurements?

The purpose of this event is to determinethe amount of flow in the room for a specific time. Indoor air measurements are taken for flow moving through the system. Its flow rate may vary after passing the filter. Regardless of the location, the speed of movement will vary. And the key role is played by the section of air ducts.

To make accurate measurements of air chooseflat area. Its length must be at least 5 sizes of the diameter of the system section. Its beginning is taken from local resistance. The distance to the next resistance should be exactly at least 2 diameters of the duct. For this, a laboratory is used, in which air measurements are taken at several points. The number of measurements depends on the diameter or length of the rectangular channel.

Types of measuring devices

Measuring devices are needed to set up the ventilation system.

The question arises, which ones? Air measurements are necessary to determine the speed of the flow, as well as the flow rate. Today in the market you can find a variety of devices. They differ in their characteristics, as well as measurement accuracy. First of all, it is necessary to pay attention to the ventilation of the room. There are devices that work with both natural and artificial airing.

Before you buy a meter,it is necessary to decide exactly where the measurement will be taken. It can occur both in the ventilation grille and directly in the duct. You should also be aware of some of the requirements that apply to the stream. For example, the speed of the flow or its temperature must comply with standard indicators.

Air measurements in the apartment are carried out by such devices:

1. Thermoanemometer It is used to measure air velocity. A special sensor is heated to a certain temperature and placed under a moving stream. Next, measure the time during which the sensor has cooled. This will be the flow rate.
2. Ultrasonic anemometer. The device is placed in the air stream. The speed measurement is due to the capture of sound frequencies at different points in the duct.
3. Wing anemometer. The flow velocity is determined by the moving impeller.
4. Pitot tube. When measuring using high-quality digital equipment. The tube is placed in a specific area where static and total pressure is measured.
5. Balometer It determines the flow rate of air that passes through a certain part of the duct.

Flow measurement in the ventilation grille

The most common instruments are the anemometer and thermo-anemometer.

They are distinguished by high accuracy and reliability. Many experts use an anemometer. In its design provides a large impeller. Its diameter can reach 100 mm. This is the main advantage of this measuring device. It is she who is able to catch air flow near the ventilation grille. With a minimum number of measurements, you get an accurate result. Therefore, it is on this device measuring air worth paying attention to.

To simplify the process, as well as to minimizeerrors it is necessary to apply additional devices. The simplest of these is the funnel. It has a simple design that allows you to determine the flow of air in just one measurement. This feature saves time specialist. In some cases, it is necessary to make measurements of the air temperature in the room to obtain more accurate measurements.

It happens that they must be produced indifficult places. In such cases, use a telescopic probe. Thanks to its long base, it is possible to reach difficult places and make both measurements of atmospheric air and directly in the duct.

To simplify the procedure, you must purchase thosedevices that determine the flow rate due to automation. The final result is displayed on an electronic scoreboard. There is no need to make additional calculations. The device will show the average number of three measurements. In the absence of these functions, the calculation is made independently.

Duct Flow Measurement

Before starting the operation, you need to make surethe presence of corresponding holes in the duct. They are necessary for the procedure. The diameter of the hole must match the diameter of the measuring device.

As mentioned earlier, it is important to choose a place. If the duct does not have the corresponding holes, they must be done independently. This is done with a drill. So how to choose a place? The hole should be on the straight section of the duct, whose length is equal to 5 of its diameter. It is located at a distance of 3 pipe diameters.

Unlike measurements in the ventilation grille,in this case, wing anemometers are used, where the working element has a small diameter (approximately 25 mm). During the procedure, thermoanemometers are also used, in the construction of which a pneumometric tube is provided.

Another device is the differential pressure gauge. It is used when the flow velocity is higher than 2 m / s. Therefore, it is better to use the previous options.

If the duct is located at a high distance, for example under the ceiling, then use a telescopic umbrella.

It can be extended to certain distances, which simplifies the measurement process. If the process will be performed using a pneumatic tube, it is necessary to take care of its length in advance.

Tips for Using Measuring Instruments

It happens that the air stream containslarge amount of dust. In this case, do not use the PAN or the Pitot tube for measuring. Why so? In the tube that is inserted into the duct, there are small holes that serve to measure the total pressure. When dusty air condition these holes quickly become clogged, and the measurement result will not be accurate.

Thermoanemometers are used in those ventilationsystems where the air velocity is higher than 20 m / s. This measuring device contains a temperature sensor, which is a sensitive element. Therefore, with a strong flow rate, it can collapse.

Before starting measurements, you need to carefullyget acquainted with the technical documentation of measuring devices. It is there that contains indicators of permissible temperatures, flow rates, and a description of the environmental conditions in which they can be used.

If these rules are not followed, measurements will not be accurate, or the device may fail.

In systems in which heated air moves,for measurement it is better to use pneumometric tubes. They are made of stainless steel, and therefore are a reliable device. At the same time they should not contain elements of plastic, as under the action of high temperatures, they can be destroyed.

When conducting tests related to the measurementflow rate and air flow, it is necessary to ensure that the sensitive element of the device is directed towards the flow. If this rule is not followed, the results will not be accurate. The more the sensor deviates from the required conditions, the greater the error.

Hatch for measuring air parameters

Another assistive deviceis a hatch. As a rule, its location is foreseen by designers in the preparation of a ventilation plan. But sometimes it is installed by the staff responsible for setting up the system. In practice, they use the second method, since the designers do not always correctly place the hatch.

Air gates can be installedindependently, with certain skills. For this, a hole is made in the system with a drill. Therefore, if it is installed in the wrong place, it can be easily transferred. Air hatches for measuring air parameters should be clearly visible, as well as easy to open and close. If you remove it, the diameter of the hole should ensure free penetration of the measuring device.

It happens that the hole is not used to measure the speed and flow of air. In this case, the flap is removed, and the hole is sealed with adhesive tape or rubber gasket.

Cost

Gauges have enoughhigh price. For example, the cost of a thermo-anemometer is in the range of 10,000 to 40,000 rubles. Compared with him, the wing anemometer can be purchased much cheaper, for only 6000 rubles.

The choice of measuring device depends on the characteristics of the device, as well as the characteristics of the air flow.

In addition, a device with a display and automatic calculation of the necessary data is much more expensive.

Price for additional equipment

As the additional equipment serveshatch for measuring air parameters. Its cost ranges from 100 to 300 rubles. It depends on the size of the hole through which the measurement will be taken.

Reviews

Measuring devices acquire onlySpecialists in ventilation and air conditioning. They make the adjustment of the system. Experts are satisfied with the measuring devices and there were no particular complaints about them.

The quality of the measurement depends on the person. When all the requirements are met, the result will be more accurate. To buy such a device for measuring air one time simply does not make sense, since the cost of equipment is quite high.

Conclusion

If you choose the right measuring device, thenYou can find out the speed of the flow, as well as its flow. It is thanks to these indicators, experts make a conclusion about the ventilation system. This is especially important for residential premises.

So, we found out how the flow of air in the room is measured.