According to regulatory documentation: SNiP and safety standards for the creation of ventilation systems regulate the frequency of air exchange, based on the amount of toxic components.

Process description

For an effective assessment of air exchange characteristics in industrial buildings, the value “kV” is used. This air exchange rate is the ratio of the total volume of air that comes “L” (m 3 \ h) to the total volume of cleaned space in the room “Vn” (m 3). The calculation is carried out for the accepted time period.

If during design, all calculations and the project itself are organized correctly, according to standards, then the air exchange rate for industrial premises will range from 1 to 10 units.

In addition to the calculation formulas and theoretical basis, to determine the required indicator, experts advise conducting studies of natural conditions at similar operating enterprises where there is actual data on the release of toxic vapors, gases, etc.

To determine the multiplicity index, industry documents, SNiPs, and sanitary standards are used.

Air circulation in industrial buildings

When constructing and planning buildings for future industrial needs, it is necessary to correctly calculate the ventilation routes in the premises and determine the process of air circulation. To do this, you will need such a characteristic as the air exchange rate, which is determined from tabular data on the presence of toxic substances in the space: oxides, acetylene oxides, etc.

When calculating the process of air circulation in a building, the amount of heat generated is taken into account so that the resulting amount, greater than the norm, can be removed year-round, without difficulties or obstacles.

To reduce excess heat, aeration is used. This process has become widespread in the chemical industry, for example, in thermal production areas. In this case, the air exchange rate in the warm season reaches 40-60 points due to aeration.

With such indicators of air exchange, the organization of airways, meteorological standards provided for by sanitary standards are achieved.

Thus, the direct arrangement and construction of premises subsequently influences the calculated air exchange rate; for this purpose, special working openings are provided that can be opened, guaranteeing the possibility for workers to receive fresh air and remove unfavorable elements.

Determination of the multiplicity index

When performing production and technological calculations for the main premises, the established large equipment. For example, if pumping units are installed at the main production site, without specialized exhaust ventilation, then the amount of harmful gases in the atmosphere will be 6-7 times higher than those limited by official standards.

In auxiliary, additional production premises, except for washing departments, the air exchange rate is calculated based on the exchange rate indicators.

The production must have an emergency ventilation system, which ensures prompt removal of high concentrations of harmful and toxic particles from industrial buildings. Such a system is relevant when there is a deviation from the established standards of the production route and when emergency situations. In order to exclude the possibility of the passage of unfavorable components through the connecting paths in the building, it is recommended to organize emergency exit paths without a compensatory inflow component.

Multiplicity table

Regulatory documents for calculating air exchange

The air exchange rate of the hood communication system is formed based on industry safety data and regulated sanitation standards. The air exchange rate is set individually for a specific room, according to the calculated information in the project.

In SNiP, TB and specialized standards of each specific industry and industrial design and construction, different information is given on the frequency of air exchange (hourly). All values ​​are given depending on the type of industrial premises:

• additional auxiliary premises;
• working shop areas.

Thus, the corresponding SNiP regulates the characteristics numeric values(calculated) for auxiliary premises production type.

Also, the values ​​of the air exchange rate are listed in SNiP P-92-76 for secondary buildings.

With the constant formation of toxic gases in the industrial zone and increasing degrees, the maximum prescribed value is taken as the multiplicity norm for each type of unfavorable industrial harmful emissions.

So, having the value of the total volume of the room (m 3) and the rate of air exchange, using simple mathematical formulas, you can calculate the required volume of incoming air for a certain zone, per hour.

L = n * S * N, Where:

L- required productivity m3/h;
n- air exchange rate;
S- room area, m2;
N- room height, m.

Air exchange standards for industrial premises

For industrial buildings, a general exchange system is provided ventilation system, the calculation of the needs of which is made based on the conditions of specific production and the availability of a certain quantity:

• heat;
• liquid or condensate;
• harmful particles.

If there is equipment with gas or steam emissions in the room, the amount of required air exchange is calculated taking into account the emissions:

• from this equipment;
• laid communications;
• provided fittings.

All necessary indicators are included in technical documentation premises, otherwise the data is taken from the actual parameters. This calculation is regulated by VSN21-77 and the corresponding SNiP.

If during calculations the air exchange rate exceeds ten times, it is necessary to make an adjustment to one of the construction sections of the documents. Thus, to reduce the level of industrial harmful and toxic particles, it is necessary to provide additional measures around the perimeter of the entire room.

Sanitary standards for the design of industrial enterprises

According to the rules of SNiP, allocated to industrial premises any unfavorable elements such as moisture and heat are taken into account from the calculations of the technological part of the design documentation.

If such data is not included in the technological design standards, the number of production harmful substances, allocated in the room, can be taken based on the natural collected facts of the study. Also, the required value is indicated in the passport papers of the purchased specialized equipment.

Emissions of toxic substances into space occur through concentrated and dispersed devices of the general ventilation system.

The calculation of emitted substances should include their quantity not exceeding:

1. Maximum value for cities and populated areas.
2. Indicators of the maximum amount in the air that penetrates into residential buildings through windows on the principle of natural ventilation (30% of the established limit on the amount of concentration of harmful, toxic substances in work area).

Determining the coefficient of dispersion into the working space of toxic elements present in the system at the time of release is part of the ventilation design of the enterprise. So, according to the standards, in industrial premises, provided the air volume per subject is 20 m 3, it is necessary to take into account the process of supplying outside air. So in total it should be up to 30 m3/h for each subject located in the premises. If there are more than 20 m3 per person, the amount of air supplied from outside should be at least 20 m3/h for each subject.

For a work area in which the air volume is more than 40 m 3, subject to the location ventilation windows and transoms and in the absence of toxic elements, the standards provide for a working (active) natural ventilation system.

When creating a project for a work area for industrial production purposes, in which there is no natural ventilation, and with the supply of outside air only through the existing mechanical ventilation, the total amount of air must be at least 60 m 3 /h per subject. The indicator can vary within the tabular data, but at the same time be at least one multiple of the air exchange flow per hour.

§ 4. Sanitary standards for ventilation design and methods for determining air exchange

In accordance with sanitary standards, all production and auxiliary premises must be ventilated. In production premises with an air volume per worker of less than 20 m 3, ventilation must be provided to ensure the supply of outside air in an amount of at least 30 m 3 / h for each worker, and in premises with a volume per worker of more than 20 m 3 - at least 20 m 3 / h for each worker.

In industrial premises without lights and without windows, the supply of outside air per worker must be at least 60 m 3 /h. In this case, the standards of meteorological conditions must be observed, and the content of harmful vapors, gases and dust in the air of the working area must not exceed the limit values ​​​​according to sanitary standards.

In rooms where the air environment is contaminated with dust, harmful vapors or gases or where significant heat generation is observed, the amount of air required to ensure the required parameters air environment in the work area, is determined by calculation based on the condition of diluting harmful emissions to acceptable concentrations or removing excess heat.

When installing supply and exhaust ventilation in interconnected rooms, it is necessary to ensure a certain ratio between the amount of supplied and extracted air in order to prevent the flow of air from rooms with large emissions of harmful substances or with the presence of explosive gases, vapors and dust into rooms with less emissions or into rooms without these emissions.

When installing local exhaust ventilation, the amount of air removed depends on the design of the local suction, the nature of harmful emissions, the speed and direction of their movement. In this case, they are most often guided by a certain value of the air suction speed in the local suction holes, choosing it such that the most complete capture of harmful secretions is possible.

For local suction, carried out in the form of umbrellas, shelters, cabinets and chambers, the air suction speed in open holes (openings) is taken in the amount of 0.5-0.7 m/s to remove gases and vapors that have low toxicity (alcohol vapor , ammonia, etc.), and at a rate of 1.2-1.7 m/s to remove gases and vapors of high toxicity and volatility (aromatic hydrocarbons, cyanide compounds, lead vapor, etc.). The volume of air removed L using local exhaust ventilation can be calculated using the formula L = Fv * 3600 m 3 / h,

where F is the area of ​​the lower (open) section of the umbrella or open opening, shelter, cabinet, chamber in m;

v is the speed of movement of the intake air in this opening in m/s.

The amount of air sucked out by exhaust ventilation devices from abrasive and polishing machines is calculated using the formula L = AD m 3 / h,

where D is the diameter of the circle in mm;

A is a coefficient equal to. 1.6 for abrasive machines, 2 for polishing machines and 2.4 for oscillating sanding wheels.

The air removed by local suction, containing dust, poisonous gases and harmful vapors, must be cleaned before being released into the atmosphere. The degree of purification of emissions containing dust and harmful, unpleasantly smelling substances is established depending on their maximum permissible concentration in the air of the working area of ​​production premises and in such a way that atmospheric air within the enterprise can be used in supply ventilation without preliminary processing (cleaning).

Issues related to the requirements for the design of ventilation, air conditioning, methods of aerodynamic testing of ventilation systems, monitoring ventilation efficiency, etc. are set out in the following regulatory documents:

SNiP 41-01-2003 Design standards. Heating, ventilation, air conditioning;

GOST 12.1.005-88. SSBT. General sanitary and hygienic requirements for the air in the working area;

GOST 12.1.016-79. SSBT. Work area air. Requirements for methods for measuring the concentration of harmful substances;

GOST 12.3.018-79. SSBT. Ventilation systems. Aerodynamic test methods;

GOST 30494-96 Interstate standard. Residential and public buildings. Indoor microclimate parameters.

SanPiN 2.2.4.548-96. Hygienic requirements to the microclimate of industrial premises;

SP 2.2.1.1312-03 Hygienic requirements for the design of newly built and reconstructed buildings industrial enterprises

Sanitary and hygienic control of ventilation systems of industrial premises. Guidelines No. 4425-98, etc.

Production and auxiliary premises must be equipped with supply and exhaust ventilation in accordance with the requirements of SNiP 41-01-2003. Natural ventilation can also be used for ventilation. The use of one or another ventilation must be justified by calculation and defined in the project.

The air in the working area must comply with the sanitary and hygienic requirements of GOST 12.1.005-88.

Air intake for the supply ventilation system must be carried out from the area where atmospheric air the content of radioactive and toxic substances, as well as dust, is no more than 0.1 MPC and 0.3 MPC for work areas.

The amount of air required for general ventilation of industrial premises should be calculated for each harmful factor: moisture, heat, dust, gas, as well as by the number of workers and taken into account highest value, obtained during the calculation.

The air in the work area must contain at least 20% oxygen by volume and no more than 0.5% carbon dioxide.

Ventilation units installed after reconstruction or overhaul, must be tested to determine their effectiveness and reliability in operation.

A passport must be drawn up for each ventilation system indicating technical parameters and the procedure for its operation and maintenance is determined.

Ventilation systems must be tested:

When assessing newly commissioned systems to determine compliance with design data;

During a routine inspection of sanitary and hygienic working conditions (at least once every three years);

When investigating cases of occupational poisoning;

At the request of state supervisors;

If there are violations in normal operation systems, etc.

During work technological equipment all main supply and exhaust ventilation units must operate continuously. If the ventilation systems are faulty, the operation of technological equipment, the operation of which is accompanied by the release of dust and gas, is prohibited.

If the ventilation unit is stopped or the concentration of harmful substances increases above sanitary standards, work in the room must be immediately suspended and people removed from the room.

Air sampling to determine temperature, humidity and air velocity in workplaces should be carried out systematically both under normal operating conditions and in cases of change technological mode after reconstruction and major repairs ventilation units in accordance with MU No. 4425-98.

Heating

Heating involves maintaining in all industrial buildings and structures (including crane operator cabins, control panels and other isolated rooms, permanent workplaces and work areas during main and repair and auxiliary work) a temperature that meets established standards.

The heating system must compensate for heat loss through building fences, as well as ensure heating of the cold air entering and leaving the room, raw materials, materials and workpieces, as well as these materials themselves.

Heating is arranged in cases where heat loss exceeds
increase heat generation in the room. Depending on the coolant, heating systems are divided into water, steam,
air and combined.

Systems water heating the most acceptable from a sanitary and hygienic point of view and are divided into systems with water heating up to 100°C and above 100°C (superheated water).

Water is supplied to the heating system either from the enterprise’s own boiler house, or from a district or city boiler house or thermal power plant.

System steam heating Suitable for enterprises where steam is used for the technological process. Steam heating devices have high temperature, which causes dust to burn. Radiators, finned pipes and registers made of smooth pipes are used as heating devices.

In production areas with significant dust emissions, devices with smooth surfaces allowing for easy cleaning. Finned radiators are not used in such rooms, since the settled dust due to heating will burn, emitting a burning smell. Dust at high temperatures can be dangerous due to the possibility of ignition. Coolant temperature when heating by local heating devices should not exceed: for hot water- 150°C, water vapor - 130°C.

Air system heating, characterized by the fact that the air supplied to the room is preheated in heaters (water, steam or electric heaters).

Depending on the location and design, air heating systems can be central or local. IN central systems, which are often combined with supply ventilation systems, heated air is supplied through an air duct system.

Local An air heating system is a device in which an air heater and a fan are combined in one unit installed in a heated room.

The coolant can be obtained from a central water or steam heating system. It is possible to use electric autonomous heating.

In administrative premises, panel heating is often used, which works as a result of heat transfer from building structures, in which pipes with coolant circulating in them are laid.

Air and air-heat curtains ( air curtains with air heating) are provided at permanently open openings in the external walls of premises, at gates and openings in external walls without vestibules and opening more than five times or for at least 40 minutes per shift, at technological openings of heated buildings and structures built in areas with the estimated outside air temperature for heating design is 15 degrees. C and below, as well as with appropriate justification and at higher design temperatures of outside air and for any duration of opening of gates and other openings.

Brief summary of SNiP on ventilation (sanitary norms and rules).

In what cases do SNiPs provide for the installation of forced ventilation?

• if it does not allow achieving the required microclimate parameters in terms of cleanliness, humidity and pollutant content;
• if the building or structure has areas and rooms in which there is no natural replacement of air;

SNiP ventilation on temperature standards.

When jointly designing, SNiP regulates the use of backup (duplicate) fans or the use of at least two heating devices. This is done in case one of the fans fails, and in this case, SNiP ventilation allows a temporary decrease in air temperature, but not less than twelve degrees Celsius.

Ventilation SNiP on backup fans.

• if during an emergency shutdown the operation of devices, units and equipment automatically stops, technological processes which involve the release of polluting vapors, gases and dust-air mixtures into the air;
• if installed in the building includes emergency ventilation capable of providing a capacity of at least fifty percent of the capacity of the main system;

SNiP ventilation on fire safety.

In pursuit of comfortable conditions inside offices and residential premises, one cannot do without properly organized air exchange. In other words, inside them there must be a correctly calculated, adjustable system ventilation. For indoors for various purposes are guided by the relevant regulatory literature, but first let’s look at what constitutes air exchange.

Air exchange concept

Air exchange is a quantitative parameter characterizing the operation of the ventilation system in enclosed spaces. In other words, air is exchanged to remove excess heat, moisture, harmful and other substances in order to ensure an acceptable microclimate and air quality in the serviced room or work area. Proper organization air exchange is one of the main goals when developing a ventilation project. The intensity of air exchange is measured by the multiplicity - the ratio of the volume of supplied or removed air in 1 hour to the volume of the room. The ratio of supply or exhaust air is determined by regulatory literature. Now let's talk a little about SNiPs, SPs and GOSTs, which dictate to us the necessary parameters to maintain comfortable conditions in office and residential premises.

Air exchange rates

Currently, a lot of literature has been published; let’s look at just a small part:

Modern buildings have high thermal characteristics, airtight plastic windows to save space heating costs, which inevitably leads to the tightness of the room itself and the lack of natural ventilation. And this, in turn, leads to air stagnation and the proliferation of pathogenic microbes, which is not allowed by sanitary and hygienic standards, and to maintain good health in stuffy room It's unlikely to succeed. Therefore, in modern residential buildings must be provided supply valves in external enclosures with natural impulse, and in office premises one cannot do without a supply and exhaust mechanical ventilation device. All this is necessary to create comfortable conditions for people to stay in these premises.

Living spaces

The ventilation system for residential premises can be: with natural air inflow and removal; with mechanical stimulation of air inflow and removal, including combined with air heating; combined with natural inflow and removal of air with partial use of mechanical stimulation. IN living rooms air flow is ensured through adjustable window sashes, transoms, vents, valves or other devices, including autonomous wall air valves with adjustable opening. Air removal is provided from kitchens, restrooms and bathrooms. The amount of air exchange in living rooms, according to more than 20 m².

Kitchen

Minimum air exchange rate in a kitchen equipped electric stove, according to 60 m³/hour, in case of gas stove, it will be 100 m³/hour. Air flow is ensured in the kitchen, just like in the living rooms. Since cooking produces steam, as well as volatile particles of oil or other fats, the air from the kitchen should be removed directly to the outside and not enter other rooms, including through ventilation duct. In order for the natural draft to be sufficiently stable, the channel must be relatively high (at least 5 meters). Often in kitchen area installed above the stove exhaust hood, helping to more effectively remove excess heat from the room. In order to prevent the flow of air into higher-lying apartments, an air seal is made (a vertical section of the air duct that changes the direction of air movement), usually in a building design.

Bathroom and laundry

The air in the bathroom and laundry room contains unpleasant odors, humidity and harmful emissions from household chemicals, therefore, like the air from the kitchen, it must be removed outside without the possibility of entering other rooms. An air seal is also installed in the exhaust ducts of these rooms. From the bathroom room, according to , the air exchange rate will be 25 m³/hour, and from the laundry room 90 m³/hour. Supply air enters these rooms by flow from living rooms through open door or through cracks in the doorway.

Office rooms

The amount of air exchange for offices, administrative buildings much higher than for residential buildings. This is because the ventilation system must more effectively cope with the large volume of heat generated by numerous employees and office equipment. And a sufficient amount of fresh air has a positive effect on both people’s health and the work process as a whole.

For ordinary office premises 40 m³/hour per employee is accepted, if it is possible to periodically ventilate the room through window sashes, transoms, vents, or 60 m³/hour per employee, if this is not possible.

Modern office buildings cannot be imagined without organized system ventilation, which must meet the following requirements:

• Ability to provide required quantity fresh air.
• Filtration, heating or cooling, and, if necessary, humidifying the supply air to comfortable conditions before supplying it to the room.
• Installation of both supply and exhaust ventilation from office premises.
• Installations must be low noise and comply with the requirements specified in.
• The location is convenient for servicing ventilation units.
• Automatic control and weather-dependent regulation.
• Economical consumption of heat and electricity.
• The need to be compact in size and, if possible, fit into a business interior.

A correctly calculated air exchange rate is vital inside closed premises, because it allows you to remove exhaust air contaminated with various technical fumes, particles of carbon dioxide emitted by humans, odors of consumer products and life activities, heat from equipment and products, as well as many other sources. If we take into account all these parameters, then thanks to the operation of supply and exhaust ventilation it is possible to maintain optimal performance indoor air, creating a comfortable microclimate.