Measurement of air in the room. Airflow measuring port

An important factor for a comfortable life of a person is 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

The ventilation and air conditioning systems should function for a long time. For this it is necessary to carry out a professional adjustment, as well as timely maintenance. The list of technical works also includes air measurements. This procedure takes place in accordance with the developed methods.

Flow rate

The movement of air through the system occurs at a certain rate, influenced by various factors. First of all, it depends on the constructive solution of the ventilation system (that is, the cross-section and the length of ventilation ducts). These factors influence the air flow. To determine the flow velocity, it is necessary to measure the air, namely its dynamic pressure at several points. The averaged index and will show the air speed in the system.

It should be noted that this indicator for the room is important for living rooms. In them, air flows unidirectional flow. Air measurements in the room are made, first of all, for residential areas. Here, an equidirectional flow occurs.

Why measure air flow?

The purpose of this activity is to determine the amount of flow to the room for a specific time. Air measurements in the room are made for the flow moving through the system. Its consumption can vary after passing the filter. Regardless of the location, the speed will change. And the cross-section of air ducts plays a key role.

To make accurate air measurements, select a flat area. Its length should be not less than 5 times the diameter of the section of the system. Its beginning is taken from local resistance. The distance to the next resistance must be exactly at least 2 duct diameters. For this, a laboratory is used, air measurements in which are made at several points. The number of measurements depends on the diameter or length of the rectangular channel.

Types of measuring instruments

To configure the ventilation system, measuring devices are necessary.

The question arises, which ones? Air measurements are necessary to determine the flow velocity, as well as the flow rate. To date, on the roar, you can find various devices. They differ in their characteristics, as well as in the accuracy of the measurements. First of all, it is necessary to pay attention to airing the room. There are devices that work both with natural and artificial ventilation.

Before acquiring a measuring instrument, it is necessary to determine exactly where the measurement will be made. It can occur both in the ventilation grate and directly in the duct. You should also be aware of some of the requirements that are imposed on the flow. For example, the flow velocity or its temperature should correspond to the normative parameters.

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

1. Thermoanemometer. It serves to measure the speed of air movement. A special sensor is heated to a certain temperature and placed under a moving stream. Next, measure the time for which the sensor has cooled down. This is the flow rate.
2. Ultrasonic anemometer. The device is placed in the air stream. Measurement of speed occurs due to the trapping of sound frequencies at different points of the duct.
3. Vane anemometer. The flow velocity is determined by the moving impeller.
4. Pitot tube. The measurement uses high-quality digital equipment. The tube is placed on a certain section, where the static and total pressure is measured.
5. Balometer. It determines the air flow that passes through a certain section of the duct.

Flow measurement in the ventilation grate

The most common devices are the anemometer and thermo-anemometer. They are distinguished by high accuracy and reliability. Many experts use just an anemometer. In its design, a large impeller is provided. Its diameter can reach up to 100 mm. This is the main advantage of this measuring device. It is she who is able to catch the air flow near the ventilation grille. With the minimum number of measurements, the exact result will be obtained. Therefore, it is worth paying attention to this air metering device.

To simplify the process, as well as to minimize errors, it is worthwhile to use additional devices. The simplest of these is the funnel. It has a simple design that allows you to determine the airflow in just one dimension. This feature saves considerable time for a specialist. In some cases, it is necessary to measure the room air temperature to obtain more accurate measurements.

It happens that they need to be produced in difficult places. In such cases, a telescopic probe is used. Due to its long basis it is possible to get to difficult places and make both air measurements and directly in the duct.

To simplify the procedure, it is necessary to purchase those devices that determine the flow rate due to automation. The final result is displayed on the electronic scoreboard. There is no need to make additional calculations. The instrument will show an average of three dimensions. In the absence of these functions, the calculation is performed independently.

Duct flow measurement

Before starting the operation, make sure that there are adequate holes in the duct. They are necessary for the procedure. The diameter of the hole must correspond to the diameter of the measuring device.

As mentioned earlier, it is important to choose a place. If there are no holes on the duct, they must be done by yourself. This is done with a drill. So, how to choose a place? The hole should be on a straight section of the duct, the length of which is equal to its 5 diameters. It is located at a distance of 3 pipe diameters.

In contrast to measurements in the ventilation grille, in this case, an anemometer is used, where the working element has a small diameter (about 25 mm). In the procedure, thermal anemometers are also used, in the design of which a pneumometric tube is provided.

Another device is a differential manometer. It is used when the flow velocity is above 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 is performed using a pneumatic tube, it is necessary to take care of its length in advance.

Tips for using meters

It happens that the airflow contains a large amount of dust. In this case, do not use a thermo-anemometer or a pitot tube to measure. Why so? In the tube that is inserted into the duct, have small holes, used to measure the total pressure. In the dusty state of air, these holes quickly become clogged, and the measurement result will not be accurate.

Thermal anemometers are used in those ventilation systems where the air speed is above 20 m / s. This meter contains a temperature sensor, which is a sensitive element. Therefore, at a strong flow rate, it can collapse.

Before starting the measurement, you should carefully read the technical documentation of the measuring instruments. It contains the parameters of admissible temperatures, flow rates, as well as a description of the environmental conditions in which they can be used. If these rules are not observed, the measurements will not be accurate, or the device may fail.

In systems where heated air moves, it is better to use pneumometric tubes for measurements. They are made of stainless steel, and therefore are a reliable device. In this case, they should not contain plastic elements, since they can be destroyed during the action of high temperatures.

When conducting tests related to the measurement of flow velocity and air flow, it is necessary to ensure that the sensor 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 necessary conditions, the greater the error.

Airflow measuring port

Another auxiliary device is the hatch. As a rule, its location in advance provides for the designers in drawing up a ventilation plan. But sometimes it is installed by the workers responsible for setting up the system. In practice, the second method is used, since designers do not always correctly place the hatch.

The hatch for air measurements can be installed independently, with certain skills and abilities. To do this, make a hole in the system with a drill. Therefore, if it is installed in the wrong place, it can easily be moved. The hatch 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 that the measuring device is free to penetrate.

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

Cost

Control measuring instruments have a fairly high price. For example, the cost of a thermoanemometer is in the range from 10,000 to 40,000 rubles. In comparison with it, a wing anemometer can be purchased much cheaper, for only 6,000 rubles.

The choice of the measuring device depends on the characteristics of the device, as well as the characteristics of the air flow. In addition, the device with a display and automatic calculation of the required data is much more expensive.

Price for additional equipment

As additional equipment is a hatch for measuring air parameters. Its cost is in the range from 100 to 300 rubles. It depends on the size of the hole through which the measurement will be carried out.

Reviews

Measuring instruments are purchased only by specialists in ventilation and air conditioning. They are the ones who make the adjustment of the system. Specialists are satisfied with the measuring instruments and there were no special complaints against them. The quality of the measurement depends on the person himself. When all 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, you can find out the speed of the flow, as well as its flow rate. It is thanks to these indicators, experts conclude on the ventilation system. This is especially important for living quarters.

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