Checking the efficiency of ventilation: measurement methods and frequency

Production control or verification of the efficiency of the ventilation system is one of the main conditions for the competent use of equipment. The need to check the efficiency of ventilation systems is provided for by GOST 12.4.021-75 and SNiP 3.05.01-85. Inspections and inspections of equipment are carried out according to the schedule, which is drawn up by the administration of the enterprise. Preventive inspections of equipment are carried out on a daily basis, with the results being recorded in the journal.

The need to check ventilation

It is often difficult to find out on your own that ventilation is ineffective. The equipment can work, but it is weak to extract the exhaust air, or vice versa, it is bad to supply fresh air. Residents of modern homes equipped with central air conditioning and ventilation systems may complain of poor health, insomnia, and headaches. The cause of the ailments is sometimes hidden in the insufficiently efficient operation of the ventilation system.

At industrial facilities, dust, poisonous or fetid vapors, and heat are released into the air. Therefore, efficient operation of the ventilation system in production halls is even more important. Poor-quality removal of harmful emissions from the workplace can lead to injury to personnel, the development of occupational diseases and even death. Visual methods of checking ventilation are usually not effective enough.

It is necessary to check the efficiency of the ventilation system before the audit of the sanitary and epidemiological authorities.

Purpose of the ventilation test

During performance checks of ventilation systems, malfunctions are detected that can lead to industrial accidents or other undesirable situations. The check shows whether the ventilation efficiency was calculated correctly at the design stage, whether the equipment can cope with the load and whether it delivers the required thrust.

The main purpose of measuring the efficiency of ventilation systems is to determine the air flow and pressure losses in the system and mines.

Industrial ventilation systems are a complex combination of high-precision electronics and mechanics, consisting of dozens of elements. It is impossible to assess the efficiency of ventilation without specialists.

The effectiveness of the ventilation system is checked by a licensed inspection. From the customer organization, there is one specialist in the maintenance of the system, who is well acquainted with its design and the locations of the main components. If the enterprise has more than ten ventilation units, the help of an electrician is also required. Based on the data, a malfunction report and a table of the frequency of air exchange in production workshops are filled in. Some laboratories offer to immediately draw up a cost estimate for troubleshooting and increasing the efficiency of the ventilation system.

Ventilation check frequency

Instrumental testing of the efficiency of ventilation systems and mines is carried out:

• in rooms with the release of flammable, explosive, radioactive or toxic substances of I-II classes - Once every 30 days;
• in rooms with supply and exhaust systems - Once every 12 months;
• in rooms with a natural or mechanical general exchange system - Once every 36 months.

Testing the efficiency of ventilation systems is a combination of instrumental and laboratory measurements.

The ventilation efficiency is checked by the measurement method:

• air speed in ventilation ducts and air ducts;
• air exchange rate (calculated)

Measurement indicators can be either increased or decreased, and in both cases they indicate insufficient ventilation.

A set of verification measures:

• Checking the natural ventilation system. It is carried out when the building is put into operation. The results are entered into the act of primary examination;
• Checking the artificial ventilation system. The condition and operability of all components of the supply, mixed or exhaust ventilation is checked. The data are recorded in the laboratory measurement protocol. The client receives a ventilation certificate and an opinion on compliance or non-compliance with design standards.

Most often, the energy efficiency of the ventilation system is checked in two stages. At the first stage, the most noticeable shortcomings are revealed:

• damage to flexible elements;
• leakage of housings and air ducts;
• insufficient number of drive belts;
• imbalance of fans.

All defects are entered in the list of defects. After the correction of which, the second part is carried out: an instrumental test of the efficiency of the ventilation system.

In some cases (if the client cannot eliminate the shortcomings in a short time), the check is carried out in one stage. Then all defects are recorded directly in the protocol for measuring the efficiency of the ventilation system.

Carrying out works

To assess the efficiency of the ventilation system, the following measurements are carried out:

• Microclimate parameters in rooms served by ventilation. Measures the level of carbon dioxide in the work area and outside;
• Air composition. This indicator is usually measured at industrial enterprises, aerosol and gas analyzes of the composition of the air in working rooms are carried out;
• Aerodynamic tests. They are carried out according to the method of GOST 12.3.018-79.

Measurements of the efficiency of the ventilation system are carried out through pneumometric holes located along the most probable axis of symmetry of the air flow in the branches of the air ducts. If the locations for measurements are not determined correctly, the calculation error increases, making them useless.

To determine the parameters of the air environment, air samples are taken during working hours, at the locations of personnel. Sometimes up to 5 samples are taken at each sampling point. Samples are taken using aspirators or draft inducers.

To conduct an instrumental test of the efficiency of the ventilation system, the following equipment is required:

1. roulette;
2. flashlight;
3. thermometer;
4. micromanometer or differential pressure gauge;
5. pneumometric tubes;
6. funnel anemometers;
7. tachometer.

All the results of instrumental testing of the efficiency of the ventilation system are entered into a summary table. Many companies immediately make an electronic version of the act, since the calculation of the ventilation efficiency is carried out by a computer using special programs. You can call them and they will specifically tell you how to check ventilation in an apartment or house yourself.

Non-device ventilation control

Sometimes, in practice, testing the efficiency of ventilation is carried out by a non-device method.

The operation of the exhaust fans is checked with a piece of paper. If it is held on the ventilation grill, there is a draft. But this is not an objective way. The leaf at the outlet of the duct is held not by the movement of air, but by the pressure difference in the room and in the ventilation duct, sometimes created by gravitational pressure.

Therefore, you can really notice the effect of the exhaust ventilation using a smoke test. A cigarette is lit under the exhaust outlet. If the smoke is directed towards the grate, ventilation works satisfactorily. Otherwise, the entire room is gradually filled with smoke.The verification of the ventilation efficiency by the method described above is rather approximate. Its results are not recorded in writing and are not used to calculate ventilation efficiency.

Ventilation efficiency

The ventilation energy efficiency is called the air exchange rate.

The ventilation energy efficiency is calculated by the formula:

K = (Tu-Tpr) \ (Toz-Tpr),

Where TO- ventilation energy efficiency coefficient,Tu - the temperature of the exhaust air outside the serviced area, in degrees Celsius,Tpr - supply air temperature,Toz - air temperature in the serviced area.

See the video for why ventilation efficiency can drop significantly.